I would expect with a group of orchestra size, one or two objections to a particular piece would get outvoted, unless you've gone down the route of any objections and the song gets sidelined?
Personally, I'm all about the music and the quality thereof. Would I play Two Little Boys or Do You Wanna Touch Me? No, absolutely not. Have I played MJ tunes? You bet.
So I guess I do draw my own lines, but they're fairly broad and I've not yet had any requests for Rolf Harris or Gary Glitter material, so win/win.
I really don't get the objection to Two Tribes. I'd be inclined to ask the objector to do one. Name a time when there wasn't a war going on somewhere.