When trying to persuade people not to fulminate and whatnot, I usually make an "even if you're right" argument: "even if you're right about $topic, please don't post the way you just did, because it's bad for the community". It doesn't mean I actually think they're right.

A harder-nosed way to say it would be: "it doesn't matter if you're right or wrong, you broke the rules and that's that". But it usually works better to include the possibility that the commenter is right. It costs nothing (the moderation point is the same either way) and it signals "I understand your point of view and it's not my purpose to dispute it". In this way you're standing alongside the other person, persuading them, instead of standing opposite, berating them.

It's also more efficient because by explicitly separating the two things (being right vs. following the rules), there's less energy for the otherwise inevitable objection, "you just don't like what I posted because you disagree with it".

So when I said "billionaire troll" it was not to agree, but rather to say "see? I understand your point of view, but you're participating in a community where we all have to take care of the ecosystem—you can't just toss lit matches or trash the place". Reflecting someone's point back to them in language they recognize is a more effective way to show you understand their point of view than merely saying "I understand your point of view". Nevertheless, the operative word in the sentence remains "but".

Of course, if you go too far in doing that, you run the risk of upsetting the other side, so you have to thread the needle. I probably should have used a more neutral phrase.