Never new free speech was optional. Since times of the middle ages were hectoring kinds with various success.

This has absolutely nothing to do with free speech. Notice how he is free to complain about the conference using his handle on his own blog without consequences?

I can scream "Futurestack.io sucks balls" all day with no legal consequence. (HN would kick me off, rightly, for doing so in every thread.)

That's different than "pretend(ing) to be them", which are his words to describe what he did. Until that point, he had the moral high ground.

Free speech protects you from the government, not from Twitter. Twitter can suspend any account they want, just like Hacker News can delete any comment on this site if they want.