And as with most moderation, how explicit can "I" be when advocating for genocide before getting booted? Do I have to just not spout slurs, or do I have to hide it even better?

I think moderators would do nicely to consider that not all negativity manifests as "niceness". If I were to say "trans women are just gay men trying to score straight men" (a real opinion of some) there's nothing contained just within that statement that makes it "un-nice", but the thought expressed is exceedingly vile. If someone else then replies "You're a horrible bigot" that would very much be a break with "niceness" or civility - is that allowed?

Moderation is harder than it looks, and I've seen forums descent into racist hellholes because moderators only cared about civility and niceness. This has slowly become my number one concern with new forums and places of discussion.