Under my moral premises, that you may or may not agree with: he’s wasting the work of other people, a potential source of food, and the life of an animal for the sake of something that could be achieved with his own hands, literally. That wastefulness is what makes it immoral for me.

Other people however might consider this immoral as it’s masturbation, or because using dead flesh to do so is taboo.

I like this example however because, regardless of the reasons, there’s a high chance that someone will consider it immoral. And yet even then it’s hard to claim that it should be illegal.