It's pretty easy to prevent that though: ban the N word and the K word, the derogatory word for Jews. That gets you 90% of the way there. You'll put off the types that drop into communities just to shit the place up. The rest of it is just letting people be themselves and the emergent culture that comes along with it. Just ban 2 words, you don't need an endless CoC to prevent the toxicity, those are generally for enforcing much more strict ideological conformity.