What’s wrong with having a mod that removes the skin color selector? I get people care about race and stuff, but is it really necessary to force everyone to have a skin colour selection option if they don’t want a skin colour selection option? You’re not going to make a racist see clearer by forcing them to do something that only affects them.

You have it in your own question. It is hateful. It was made by the hateful for the hateful to perpetuate a hateful idea. You might even call it a kind of hate speech, which probably means it violate Nexus’s terms. Even if it doesn’t, it’s icky af. And Nexus is entirely in their right to refuse hosting it. The nod creator is still free to use their own mod and share it in other ways, but Nexus should not be forced to host it.