homosexual people may engage in high-risk sexual behavior, homesexuality itself is not an illness. Similarly, heterosexual people may also engage in high-risk sexual behavior, but it'd be hard to find any doctor (or layman) who'd describe heterosexual people as ill.
There would have been nothing wrong if the doctor in question had, with consent, described some sexuality-based risky behavior that had led to an illness he diagnosed. But that's not what he did; what he did was declaring homosexuality an illness by including in his report this offensive line, "Current illness: homosexual."
