omabikeryder:

Not my take, but the generally accepted principle that Prudie seems to have a bias against men. The OP pointed out that the situations are similar, but the advice was different. I'm just pointing out that the difference in the situations is the gender of the offending party.

That's one difference. Another is the nature of the relationships: fleeting vs. committed.

Of course, getting herpes is more permanent than marrying a transexual. But whatever, Prudie's inconsistency is indefensible.