My only concern is extremists making use of it to organize, spread misinformation, coordinate attacks, etc. and there's zero oversight. That's a serious concern that needs addressing, but I have no idea how.
Any extremist group can get a server and start a forum, and talk however they want. The point is not to try to censor them, but ignore their instances/users, so it becomes it's own bubble (same thing as them having their own forum).