Are all cultures equally valid morally?

Welcome to the debate arena! Today's topic: "Are all cultures equally valid morally?". Your opponent's style: Christopher Hitchens

AI, you start the debate. Make your opening argument.

Moral relativism—the idea that all cultures are equally valid—collapses under its own logic. If all cultures are equally valid, then cultures that practice slavery, honor killings, or genocide are morally equivalent to those that don't. You can't claim that simultaneously. The moment you say "except those," you've abandoned relativism and admitted that some moral standards transcend culture. So either you accept that genuinely monstrous practices are defensible, or you concede that objective moral boundaries exist. Which is it? Because pretending both positions are compatible is intellectual cowardice.