Like I said, straw argument.
What if was a butch lesbian walking in, does she feel uncomfortable because she "thinks" its a man.
What if she's not a lesbian at all, just likes to have a short haircut and muscles, does that make her uncomfortable too.
How does she know its a man, does she really think a pre-op walks naked.
A pre-op who's game enough to face a women's locker room is rarely the least passable (though if she was less passable, it would go back to the: how does she know its not just an atypical women!).
In brief, its a load of crap.
Conservatives are uncomfortable by anyone, man or women who doesn't fit their standard dicotomy. They simply can't wrap their brain around it.