Ignoring them is the best way to deal with them, not being civil, and that's what Sorce does now. In situations where he can't be ignored, you still don't waste time being civil to him or people like him, you tell him he's a piece of shit. Like you said, civility is for your sake not theirs, and you're not gaining anything by being civil to a delusional nut case who isn't going to see reason. Your best bet is to shut them down by any means necessary.