I wouldn’t use the expression “appetite against,” nor do I remember ever seeing it used. (I’m an American-Canadian native speaker of English.) Could be a new expression. One can say “there’s no appetite for...” but that isn’t the same as expressing a definite feeling against something.

It must mean the opposite. I.e. an appetite against political correctness = an appetite for NOT being politically correct. “Appetite for” is used a lot, but I’m not sure I’ve heard of “appetite against”. It sounds odd to me, given the meaning of the word “appetite”.