Why am I searched every time I go to Australia?

A couple of reasons spring to mind. The obvious one would be this is a person engaged in work that gives access to restricted materials and who also appears to frequently travel to countries like Russia and China, at least from what they have written on the rest of their website. That alone might warrant suspicion of espionage or simple carelessness in handling restricted data. They also seem to be very active in online spaces and possibly they have been skirting close to the line of what they have shared, and thus triggered an alert. It wouldn't be the first time I've been aware of people thinking they are sharing harmless things that in reality are restricted. Of course there are darker possibilities here, and a guilty person presumably wouldn't admit to them in a blog.

Australia is also a member of the Five Eyes. It is not impossible that someone in the US asked Australia to add him to their list.

If nothing else, this article has further cemented in my mind the idea that you should never cross a border with a phone or laptop that you give a shit about. Ship your devices ahead of you, or stash digital copies of any important data somewhere you can get to with a clean device you bought at the destination.

This really sucks.

It's like some of the most noble officials of previous generations who staunchly fought WWII to reverse the spread of authoritarianism, have now been replaced by a current crop who is trending in the opposite direction that their ancestors fought & died for.

I started to read the article. Then I thought "may be he is working with cryptography and that is why he is searched". And a sentence or two later he writes "Advanced Mathematics" and then "GPS". I think that is why he is being searched.

Similarly the developer of curl was not able to obtain USA visa.

Might be because a person you have associated with in the past. I use the word " associated" very loosely. You would not be aware of the associates history for example.

i read the article, and i really think the combination of stated specialties, with dual-citizenship, sides up to a profile of concern.

-- thats not to say there should be concern. there are stereptypical profiles that ask the question, what is this person capable of doing? rather than, what does this person intend to do?

and thats the problem, its difficult to titrate intent, but capability is easy to asess

Why believe of what they say - what they say - that it is random - when turns out you on watchlist?

Because you're a dual citizen.

The author does not state how he knows he is on the MAL. It’s an important part of the story. If he doesn’t actually know, it’s more than possible it is random.