Who are we to say our culture is better than anyone elses, you may ask. Well, it's part of my culture to think it's better than other people's culture. Who are you to say that my culture is wrong? I mean, that was the proposition we began with right..
It's bizarre to me that people who start walking down the relativist road nonetheless feel they have some sort of basis to judge that a certain culture, typically the aggressor in a struggle, is wrong. If you accept relativism, then there is no objective basis on which to say a culture, whether it is an aggressor or not, is wrong.
It's not even accurate to say that the aggressor is intellectually wrong for not accepting relativism. It's perfectly easy to accept that morality is relative depending on culture and still accept that part of your culture involves believing yourself superior to other cultures. On relativism, there's no objective truth to that belief. But there's no objective falsehood to it either. It simply is what it is. But that is to affirm its existence, not take it away.
This is not the only piece of evidence suggesting that what really lies behind the smoke screen of relativism is in fact anti-westernism. Criticism of any culture, therefore including aggressor nations/cultures, is absolutely incompatible with relativism, and yet people want to make that exception. Well on relativism there are no exceptions and the fact that people want to covertly sneak that in shows their initial prejudices which the intellectual theory of relativism is being used ad hoc to justify.