The best move for management in this situation is to “promote” him, into a new role that segregates him from the rest of the team. No office space work in the basement thing, but something that makes him distinctly a different role/title, and physically gives him a small office down the hall.
It doesn’t sound like much, but any physical distance will be nice for you and others like you. It also removes depression when you know he’s the same role but not held to the same standards. Eventually all that crap takes its toll, and good people quit…or worse, they stop caring and don’t quit.
The saying one bad apple can ruin the bunch is very true in work situations.
This is exactly why I never got into Xitter or Mastodon. I’ve tried them, but it’s a lot of work sifting through stuff to try to find somebody you want to follow. And newsflash, I don’t find many people that interesting that I want to hear what they say repeatedly.
Whereas forum style I can more easily find content I enjoy, then also possibly enjoy the comments as well.
Neither is right or wrong, it’s just a different approach to online engagement.