You might be confusing Zimbabwe with South Africa... while South Africa's twisted new government gives preferential treatment to blacks, Mugabe is a tyrant just like Saddam who oppresses everyone, black or white... many blacks get just as harsh treatment as whites.
My guess is that mugabe oppresses blacks and whites, but my guess is that the blacks have a choice to crossover and join mugabe and his thugs (not an appealing choice, but a still a choice) while the whites don't have this choice.
My other point is that it would be politically impossible for the US to admit the whites and not the anti mugabe blacks.
No confusion here at all. While I agree with your premise, there's no denying the fact that white people have been singled out for rape, murder, and the taking of land. When it was the other way around, there was outrage around the world (as there should be) .... but there is no such outrage right now. Double-standard? You bet. You are correct in your description of Mugabe as a tyrant... but I would go further. The guy is a murderer and a thug. The sooner he is taken out, the better everyone will be ... black and white.