The Alt-Right: Blacks have inferior genes. That not racist, it's science! Blacks aren't oppressed! Click bait article: 10 Racist things that White people do. The Alt-Right: That's Anti-White racism! Stop oppressing me!
Because you created a situation where a single Black person was in a position of power. Black people (as a class) don't have access to systems of power so White people (as a class) don't experience discrimination the same way. You can cherry pick spacific individual cases.