Well, if it were genuinely possible, and there's no evidence it is, then maybe, so long as people have the right to not change it either. And if it were possible and people were doing it, I'd be tempted to coax people into becoming bisexual. If for no reason other than, if you must be monosexual, why not try both sides and see if you have a genuine preference one way or another? And you might even enjoy being bi. Also I might suggest that incels become asexual. That's not the best way to deal with their issues, but for some of them, that might put them in a place where they can find a way to deal with their issues for real.
Wait, that's not what you meant, is it? You're just looking for an excuse to pressure non-heteros into being heterosexual? Okay then.