many gay men dislike and distrust other gay men. It's certainly an internalized homophobia I guess might have something to do with rejection, etc.
There are laws in many states making a felony infecting someone with HIV, in other countries based on the Napoleonic code laws were applied about people who knew had diseases and engaged in close contact with others not concerned about infecting them.
back to legal facts and not so much to feelings how could a judge determine the client was infected with HIV by the escort and not by someone else?
Many people for sure, this was only one of his clients. Fortunately most of them used condoms and later on moved on to PrEP but we don't know.
The fact that the OP is asking what to do instead of simply reporting and that we don't know where he lives makes us wonder if anything will come up out of this.
Man jailed for life after deliberately infecting men with HIV | Crime | The Guardian
US: Michigan man who turned himself in for ‘deliberately’ infecting others, sentenced to 1.5 to four years | HIV Justice Network