Homophobia has AIDS and AIDS-related mortality as comorbidities. There exist fewer support structures for gay black men than exist for gay white men, which e.g. reduces knowledge transfer, makes it less of a cultural norm to stay on your drug regimen, provides fewer role models for how to live as an HIV-positive man.
It's also important to note another factor: our disproportionately black prison population and our epidemic of prison rape. Anal rape by multiple men, many of them with one or more other STDs, is an ideal way for an HIV infection to be transferred. HIV also gets transferred in prison through consensual sex: most prisons don't offer free condoms to inmates. The net result is the rate of contracting HIV is 10 to 100 times higher within prison than outside it.