I agree with a lot that is being said. I am pretty vers but like to BB. I try to mitigate the risks by only getting Topped by men who are on meds. I also play a numbers game, since Iam not a guy who needs to fuck daily. I usually get in sex once or twice every few months. I am content and I do give and receive skanky massages lol in between the sex. Oh, frottage is wonderful...but even that has risks (herpes.)
All you can do if you have decided to fuck this poz guy is to be ready if it all goes "tits up." Minimize the risks as much as you can and enjoy life. I hope I never get HIV (sorry guys) and I dread someone "stealthing" me, however I know it is a possibility. Just have to weigh your options and decide if you wanna take the risk, I suppose.