Right, fair point, but I mean, the "wrong side of history" narrative tends to presume that either in the long run, whatever side is right will win, or that whichever side wins will be the right one. I think that's a very dangerous assumption either way that should really not be made into the core of a moral argument. Argue from universal principles, argue from universal emotions, argue from social health, argue from self-interest. But don't argue from your eventual presumed victory as if that's a reason in itself.