It will never cease to amaze me that he is the creator of Chomsky heirarchy of Grammars that I learned in university, and I can go to youtube to find him talking about how each American president would be guilty of violating the Geneva Convention.
The contribution of the Chomsky hierarchy to computer science is highly significant. It had a big personal impact when I was learning about compilers and parsing. Any remembrance is going to keep getting flagged off of HN because of his other activities, though.
I think the flags have more been because of the poor sourcing of the actual death. It seems various people and groups heard that he died and are posting their obituaries and remembrances, but there's no real factual confirmation or details (e.g. one thing that was briefly on the front page here [1] was a link to an unsourced, now-deleted tweet from Momentum UK).