Hacker News Reader

Yes: he's filed suit against the "Center for Countering Digital Hate", also for publicly criticizing the way he runs Twitter.

He's an absolutist in his belief that he should be free to sue anyone whose speech about him he does not like.

It would be nice if others start counter-suing him personally and not his companies. Don’t make the employees suffer for his tactics.

Did he also ever take legal action after the supposed stalker incident which was claimed to be a result of the jet tracker?

In this specific round of bluster, he has filed suit against Media Matters.