Spoiler: it's racism.
Incredible
If some behavior associates with race, it doesn't mean that it is caused by race. There are plenty of African or Muslim origin people who assimilate just fine. It's just that a larger proportion than natives, some "other" groups commit more crime or live off of welfare. Race associates with less merit, yes, but doesn't cause it. Cause is merit, not race, hence not racism.
If you are unable to point errors in this line of thought, then making fun of it will unfortunately make your stance look even weaker.
I guess you haven't felt the consequences yourself yet.
This is absolute nonsense in every way, in addition to being racist and xenophobic. You aren't special because you won the lottery of what line you were born inside of. Get over yourself.
Also, unfortunately the lottery is real: while there are productive people who become wealthy mostly due to their own effort, there are many more who are just born into a well off country and benefit from the history before. But the question is, should a country that is well off somehow let everyone in to enjoy these benefits because it is "fair"? I guess your answer is yes, mine is no. I'd say, if you drew the less good lottery ticket then it's up to you to climb the ladder, rather than get into a rich country and start using its social services.
And there is no ladder to climb, it is nearly impossible to migrate legally and gain citizenship. One of the many big lies of xenophobic, racist, anti-immigration people is "they should do it the right way, come legally" when for the overwhelming majority of people it simply isn't possible, and the current admin is making it even harder, motivated purely by racism.
Another one of the big lies, one that you are doing here, is wildly overstating the extent to which they "enjoy the benefits". Mexican immigrants are not eligible for most of the services provided to citizens.
Every attempt at quantifying the impact of Mexican immigration to the US is overwhelmingly positive to the country. You have nothing to stand on but racism.
Immigrants commit fewer crimes
Also, Muslim is a religion not a race
Race and racism are terms you have brought in. (And I guess this is another reason where my arguments aren't actually "racist"?)
Dig up man
Since enforcing laws and fighting crime is what states are doing anyway, then doing them more on immigrants achieves that goal more. (The situation is of course also unfortunate for any decent immigrants, as it will be more difficult for them to enter.)
But it's you who for some reason turns the merit argument into a race one. They do conflate, yes, perhaps that is why you can't tell the difference?
There is absolutely no merit based argument against the immigrants who are here or trying to come here. It's completely about race no matter how hard you try to deny it. No one is buying this nonsense.
There are a lot of non-white british people (just like there are non-white americans), and he basically ignores that entire population. He assumes that you are only british if you are white and that london is worse now because there are less whites there. That has nothing to do with meritocracy, and arguable little to do with cultural non-fit.
There's a lot more to unpack in that article aside from just that, but that is the most blatantly obvious one.. And for what it's worth, I don't disagree with DHH on mass immigration. But he seems to have a lot more severe beliefs than just "mass immigration is bad".
There are many people who are mostly or wholly culturally British. I am not white and I live in the north of England and the biggest cultural non-fit is that my speech is obviously southern.
London does not, on the whole, feel very different culturally, from when I grew up there in the 80s. The biggest change in terms of the cultural impact of immigrants has been that of Eastern Europeans: things such as the availability if Polish food.
I do think he also supports merit based immigration, but that doesn't mean he's not racist. He also very openly supports very extreme right wing political figures that promote things like ethnic cleansing. If you look into it more, he is pretty blatantly racist.