My advice would be act now, contact some legal representation groups who are familiar with online laws, censorship, and discrimination. Tell them the details and ask if there's a case here. They'll know much better than I, if there's a legal case against this individual's actions.

Freedom of speech is definitely a sword that cuts both ways: it can protect against you being silenced unfairly, but those same protections can also be extended to someone whom you think is absolutely in the wrong. You haven't really provided too many exact details here, and that's what so many freedom-of-speech cases turn on: the details. Provide those to a legal advisor who will advise you if there's a case or not.

It isn't possible to legislate common courtesy. However, that does NOT mean that you shouldn't check with a legal professional and see if this is a violation of civil rights, or of the laws of the country in which the community operates. If it is a violation of civil rights, then the perpetrator should be stopped.