Hi, I know this is an old post so not sure if I should reply. Anyway I'm gay and struggle with POIS.
I struggle with a lot of social anxiety and haven't been with another guy for a long time, so I can't really answer.
I can't imagine that coming in contact with another guy's semen would be a problem for me though. In my case I feel it's a depletion of various brain chemicals that occurs during POIS rather than a semen allergy.