We have to assume that they are obviously targeting caucasians and Africans. If they can get this to target those two only - and NOT Chinese - then this thing will be exported every way they can, as soon as possible. This would eliminate Russia as well, giving the ChiComs nearly total victory.
Well, I'm not a doctor, nor do I play one on television. But how can they pull ethnic specific diseases beats the hell out of me. Your assertion is more than plausible, I'm sad to say.
This isn't said in jest, so please don't take it that way, but, if China killed off America, that would be like killing the goose that laid the golden egg. Who would buy their patio furniture?
Recall the SARS episode where the Chinese seemed to be getting hit pretty hard? There appeared to be a correlation to a receptor site that was homozygous dominant in most Chinese. A heterozygous individual had a much lower binding affinity. A small group from the Caucasus region are homozygous recessive for the site and can't be infected. They are also immune to to infection by Yersinia Pestia (Black Plague).
I have no doubt that bioweapons are being designed with higher probabilities of nailing specific ethnic groups in higher numbers. It would be next to impossible to guarantee precise specificity with all the mixing of various populations.
A lack of genetic diversity within a population opens the door to targeted genetic attacks. The observed value of hybrid vigor in plants has some general application to animals too.