All good points.
Although the US has just over 1 million estimated cases of HIV, a small fraction of the 400 million population, HIV is still a serious disease. The economics of treatment, as well as the undesirable effects of the disease and the cocktail, are not things to be taken lightly. The medical community is very much behind preventing disease as well as treating it, and I think the CDC is not concerned with how many cases might be transmitted each year through blood donations, but the fact that it still occurs. Again, I suspect that this issue is temporary, and that new technology will soon be able to identify new mutations rapidly, allowing all demographics do donate just the same. In the meantime, I do not believe that preventing donations by a group is infringing on any rights. If someone wants to help that much, then not being able to give blood is a minor speed bump in humanitarian efforts.
It is correct that black people account for just about 50% of cases of AIDS in the US. However, broad ethnic categories such as "black" and "white" do not take into account the type of individual that is likely to spread infection. Suppose that 75% of new HIV infections in the black category came from IV drug users. That means that of ~400,000 black persons with HIV/AIDS, 300,000 are chronic drug users. Categorizing the type of individual, rather than race, allows for comparisons between all demographics and means that these subcategories are likely to be more accurate descriptors of risk factors in group populations than more generalized ones. The fact that more blacks are at risk than other minorities is might not be a product of race, but could originate from cultural distinctions, practices, and individual preferences. Perhaps because poverty rates are higher in black communities, more are likely to abuse IV drugs and contract an infection. Does that extend to all blacks? Of course not, but it is much more likely to be a characteristic of the sub-group within that racial class, which can extend to all other situations.
So far MSM is proven to be a high risk category, along with IV drug users. Individuals with an extensive history in either category are not discriminated upon by being banned from donation. Rather statistical evidence and analysis by virologists and other researchers evaluate percentages and likelihoods of all groups before making decisions like this. I think that any respectable person who is at a high risk, would understand why he or she might be placed in such a category. It's not about taking rights away, but protecting the health of citizens as much as possible.