Besides, didn't Euronymous support bands all around the world like Sarcofago etc. Where is it suggested that he was a racist?
Black Metal existed well before Euronymous came on to the scene, so I don't really give a shit what he has to say on the matter.
I wouldn't say that black metal is for white people. But for some reason, mostly white people like black metal, or metal in general. Some Asians and latinos are into metal, but for some reason very few blacks are into metal. I think that most blacks see metal as "white man's music," and since most of them hate white people, they don't want to listen to it. Also, Africa by far has the smallest metal scene (ignoring the South African scene, which is all white). There are a couple bands from Angola and Botswana, but that's it.
There could be an African black metal band. Black metal does NOT have to be from the north. Some of the best black metal comes from the Mediterranean region, and there is also some good South American black metal, so why not an African black metal band? It would be cool if there were an African pagan black metal band with lyrics praising Ogun (the Odin of West African mythology).