It may be unsupportable, but it is not unreasonable. The Tuskegee Experiments lasted until 1972. These experiments targeted black men.
How can you say it is unreasonable for other black men (or women) to distrust the government that perpetrated these crimes against blacks?
Additionally, since there are well-known scientist that dispute the official origins of AIDS (and I am not saying they believe that the government created it to target black people--I am saying that AIDS skeptics run the gamut of beliefs about origins), it is not beyond reason to understand why certain segments of the population may be skeptical themselves.
This is not an apology, this is pure psychology. You are attempting to dismiss someone's views as quackish without investigating the origins of these beliefs. As I have correctly noted, they are neither uncommon nor, necessarily, unreasonable, given real, incontrovertible history of bioethics in this country.