Is it prohibited to visit those websites? I once was interested to understand the way radicals think, to read about their arguments, so I spent some time hanging around some radical websites.
Use Tor browser if you are going to research anything a criminal might regardless of pure motives.
If you so much as want to research lock picking, use Tor.
ISP traffic logs can and will be twisted against you in a court of law.
So "keyword" (could be a word, domain or some other pattern) X may trigger only if Y and Z was already triggered. And some keyword A may only trigger if B was NOT present.
This way you can distinguish doctors, reporters or people studying history or chemistry from those who plan something.
Or e.g. ML applied to patterns over time. Globally.
And yes I do not like it at all, HN is full of people that may likely research some kind of bomb, religion or whatever else out of pure curiosity, but since there are not many such people it can be problem in court one day.
Mix in some Snowden, your hardware stack, gag orders and the fact that we have more laws that anybody can read and you may feel like watching some stupid memes.
It's not prohibited but they notice and subject you to harassment by the system at every action with every part of the system that is integrated with their database.