Then I'd clear it up with my own comment on shitty behavior.
I've refused to watch, read, or even listen to certain fandoms when I learn their fandoms are batshit insane, purely on principle that I don't want associated with them. I wouldn't want people to have to do the same to my comic simply because of outofcontrol nutsos. I quietly enjoy things, that's just how I am, and I don't get why people can't control themselves, so. If my fandom were to start getting nutso, I'd start posting public "stop that shit" PSA's to clear them out. Only the fans who actually care would stick around anyway after I was done, so nothing lost should half my fandom bail, right?
Personally, I think creators occasionally saying such a thing is healthy. Nothing wrong with telling people to stop acting like jerks.