What’s so wrong with China defending Hong Kong and national security?

I am aware of all the legal documents you mentioned, including the Nanking treaty and the variously amended agreements from the 90's.

If that were the case, then this statement would display knowledge of how, if it were an honest statement, the Chinese haven't violated a word of any of them. Claiming without showing how the central government has violated the Basic Law as is pretended here, is very incorrect.

You are correct that initially the Brits took the Hong Kong land and people by force from the Qing dynasty (not from "the Chinese",

One and the same. A comment Western propaganda trick is to try to divorce the people from their governing system, and say "I love Chinese people, just hate the Chinese governing system." This unthought-out, irrational statement is fodder for geopolitical propagandists.

the Chinese were subjects of an absolutist monarchy - as compared to e.g. British subjects that had a much better position and being a British subject was even considered a privilege; note that later Hongkongers often considered it a privilege too).

Racist Western arrogance blinds this comment. Having the country split asunder, and stolen at gunpoint is now (if this comment is to be believed), "a much better position", even (how self-important, blind, and abusive) "a privilege". If it were truly better, why did the Chinese have to be forced by the British at gunpoint to abandon their system and their sovereignty, why not willingly run to the embrace of the "better" system?

That doesn't change anything about the fact that modern Hongkongers are a distinct group of people that would prefer to have their own state - many Hongkongers of today would actually prefer a modern version of British protectorate, regardless of how unjustified and unwanted it was at the time of its original establishment. That the Hongkongers would prefer a completely foreign ruler is very telling about China.

This is such a lie. True "independence" activists were a scant minority even at the height of rioting. If this comment truly understood HK as it pretended to, it would assert that their British affiliation was just a way to rebel by trying to anger China.

Were the people deciding, or was it decided for them?

Southern Chinese people living in HK were perfectly happy to decide to be part of China until the British forced surrender with superior military. It was decided for them by British guns, just like these racist statements are now "deciding for" HK and Chinese people how they should govern their affairs.

Did their government (the UK) act by itself or because it was threatened?

Brits threatened at gunpoint in the opium wars. This comment's history is backwards. It refuses in its estimation to grant HK the autonomy you pretend to be standing up for.

Perhaps that is why we're ignoring the legal documents -

This comment admits its ignorance, and in its hubris suggests its "ideas" have greater validity than the legal basis of HK, a region which tho these statements pretend to, have idea no about.

and as always what two superpowers decided between them might have no relevance to the actual wishes of the people on that land, as you said yourself.

Did I say that? No I did not. This statement is a lie. I said that ethnic groups have no relevance to national borders, which of course is true, unless you're a racial supremacist.

Additionally, you should re-read the document - the Chinese state is blatantly violating the agreement that was to expire in 2047.

This is reaching, and appears to know it. I've read it and have knowledge of it, unlike these comments. That's why I can say with certainty there is no violation. Make a coherent case based on the Basic Law to show China has acted inconstantly with it, is the right way, not making ludicrous bluster that avoids facts. These comments disrespectfully speak down to Chinese and speak on things about which these comments demonstrate no knowledge.

Did the people agree to it before they were "re-educated" in death camps? Do they even agree to it today?

This is foolery. "Death camps"? These statements clearly regurgitate a steady feed of uncritically-believed wholesale Western propagandist lies about China. They are irresponsibly repeating such, and are thus an instrument of such geopolitical propagandists' will.

Historically, the Chinese had the bloodiest revolution of the 20th century that gave birth to a new system they themselves created. If they didn't agree with it, they'd tear it down, as they did before. These ahistorical and inaccurate comments speak as if fronting to be a "friend of China or Chinese people" but they are anything but. The sound more like dictates coming down off a Western high horse.

You're contradicting the previous statement. It has everything to do with national borders when these are the things that define the nation in the minds of the people we're talking about.

Unfortunately for this comment, I do nothing of the sort. This is an invention of desired lies, as a substitute for coherent points. The contradiction is inherent in these comments when they pretend they are against "enthnonationalism" while that's exactly the claptrap they are promoting. However, contrary to the delusion of these statements, China is not doing.

Heh, that is exactly what the Chinese Communist party is doing and what I am opposed to.

This comment has been fed on lies. It's to the detriment of the credibility of the comment that it keeps mis-stating.

They're building the concept of "the new Chinese person" which everybody should subscribe to, and they're using this new "Chinese nationality" as a justification of their rule over the land and people, acting in the name of "national security".

Oh, lord, this is great fantasy delusion. The Chinese mandate is based on the results they deliver. My theory is these results threaten fragile-minded Westerners, who, instead of facing Chinese achievements, reflecting, and learning, prefer to feel better instead by inventing stories of "China bad", which must in part satisfy outmoded beliefs they are the best in the world.

They're trying to pull the same shit with Taiwan.

This comment lacks any understanding of history.

I personally don't think nationality, ethnicity, culture etc is a good way of determining state borders, I don't even think borders are a good idea at all. In this case however the CCP is very successful in using these arguments to justify the integration of Hong Kong (and Taiwan), which is why I am here saying it's lies.

This statement is idiotic. The Chinese case for sovereignty over HK and Taiwan is historical, not ethnic. It has zero to do with the ethnonationalist claptrap hawked in these comments.

Now I'm curious what do you have to say about Taiwan. Culturally, linguistically, ethnically etc it's very close to Hong Kong. Does that mean the Taiwanese are Chinese?

These statements suggest no knowledge of China. The case for Chinese sovereignty of Taiwan is based not on any ethnonationalist extremism as these comments, bizarrely and, frankly, quite obsessively, try to invoke, but rather on the civil war in which the defeated retreating nationalists claimed Taiwan to be an independent state, and China said, "we'll deal with you later."

The bigger game, at least in part, and which I expect very few to grasp as it runs counter to the dominant programming and propaganda, is Taiwan and China are on the same side and working together, to the deliberate deception of Western nations. Taiwan is sort of like a "safe" port for Western interests, and China benefits by keeping such in its pocket, while pretending animosity to give credibility. Taiwan is where China can try things it can't on the mainland, and engage Western interests and economics in a zone they feel safe, all disguised and protected (from the, to Western minds, "dangerous mainland") under the convenient banner of an imaginary state of conflict.

What about Austrians, they're Germans in almost everything except the name, they actually considered themselves Germans just a hundred years ago - "Austria" is the name of the land while "Germans" is a ethnocultural group. How come?

I have zero idea about that region, and so I will not speculate on it. I, at least, have the sense and respect to not proselytize about that which I know naught. The ridiculous commentary here would do well to learn from me about that. The counter-factual, ahistorical delusions about China in these statements are nonsensical, embarrassing and bordering on insane. It's deeply shameful how little knowledge is in these statements which I address here, and yet how confidently and emphatically (and worse, how suffused with the mere color of "moral righteousness") they are made. The only comment I will make to this end, is a lot of the bizarre obsession with a non-existent, alleged Chinese state-sponsored ethnonationalism, makes "more sense" (and that's a stretch) when considering the comments are most likely made through the lens of a Eurocentric historical perspective deeply informed by, and likely dealing with the unresolved socio-psychological issues around, the failed trajectory of Germany, and it's politicized ethnonationalist 20th century history. Apart from that connection, it's unclear what prompts this projection of a failed European history onto the Chinese story. However it's understandable, if unfortunate, because people need to try to understand things through lenses of which they are already familiar. The problem is, as can be seen here, is those perspectives become vulnerable to being highly distorted and just not making much sense.