GHB
I think that is the point where I would consider pressing attempted murder charges. That shit is insanely dangerous and it’s withdrawal can apparently be worst than that of fucking Heroin. Like: There are places that are otherwise very open to drugs that have zero tolerance policy on that stuff.
Can’t he just not tell them that he has it? At least in Germany that was generally the solution for gay people to donate blood: The only person who could potentially be liable would be the physician if they knew for a fact that you were lying. Which was very unlikely, considering that those red cross people rarely included the local GPs. (The legal situation might be different in other countries though, so check!)