Call me a suspicious soul, but I don't see someone doing sex work in '93/'94 with any kind of sense of self preservation having unprotected sex with a client without a condom.
HIV/AIDS was ravaging the community at that point, especially among sex workers. No glove, no love was real. Everyone knew how it was transmitted by then, and though it was after the approval of AZT, it wasn't until '97 that triple cocktail (combination) antiretroviral approach was used and outcomes drastically began to improve.
I know there are other things that could result in semen on a person, I'm not naive, but if he's claiming he had consensual penetrative sex, I'm raising a major eyebrow.
MOO