White supremacists - surprise, surprise - only cares about the idea of whiteness. They never actually care all that much about actual white people themselves.
It probably has something to do with the fact that right-wing ideology (of which white supremacism is merely one) consists of nothing more than excuses, pretexts and lies designed to protect and benefit power and privilege and nothing else.
I have two half-Thai cousins who are hardcore white supremacists. It's so weird to talk to people who are so into an ideology that excludes them in particular.