Muslims do not generally believe in cultural or moral relativism. Allah is the one true God, his moral teachings are objectively correct. Why offer them a way out that they themselves aren’t able to coherently accept?
Besides, cultural relativism is nonsense. If someone tells me it’s okay to molest children, their perspective is not “just as valid” as mine. They’re a monster.
Yes, this means a lot of people in the past, and today, are monsters. That’s extremely plausible.