Hey Loren - if you want to make your terminally flawed analogy to black rights actually work... all you need to do is to retain race-based segregation, but then make an exception where any white person who self-identifies as black has the legal right to use the black-only spaces.
That is actually a reasonable parallel. But then it shows your analogy for the complete lunacy that it actually is.
What's the person that's half-white/half-black supposed to do in such a world?
(And, no, I will not accept what the law was in Arizona for a while--they're part black so they can't marry a white. They're part white so they can't marry a non-white. The state Supreme Court noted the issue but since it didn't need to be addressed to deal with the question before them they ignored it.)