I can see Social Media CEO saying "well, I believe in free expression and I would otherwise want to allow this message, but I'm worried what the government will do to me if I do allow it. So instead I will block it."
When a platform blocks some content, some call it "censorship", while others say "hey, it's a private company and they can block what they want to. It's called 'moderation'" - but this may in fact not be something the platform wants to block - it's indirect government censorship.
I wonder how Elon will handle this. Will he be cowed by the government into censoring content they don't like? Or will he ignore them and take his chances?
"Specific Person is a real jerk! And they probably eat live frogs for fun too! What a loser!" - As long as Specific Person can effectively ignore this - meaning it's not forced into their feed, overwhelming their inbox, etc - then that's probably fine, even if untrue.
"Specific Person might live near XYZ. Definitely DON'T put any turds in their mailbox ;-) " - Pretty clearly an invitation to real-world harassment, which is not okay and should not be abetted by any platform.