Moral relativism is merely an idea. Not a reality. The point is that saying "it's their kind of relative morality" makes for a very poor excuse when used to rationalize situations that result in harm to other beings. It is usually just one side who controls that set of morals, while the victims are stuck with it. That goes for every atrocity ranging from genocide to these crush videos. If it is a society's morals to torture and kill... then it isn't morality at all. It's barbarism.