I was going to mention butch cis women (not all of whom are lesbians, even). I've never been challenged in a bathroom or locker room... but I have several friends who have been, and all are cis and masculine-looking. Heck, one of my college friends grew her hair long b/c she was tired of being yelled at in bathrooms. The assumption that banning anybody who "looks like a man" will keep out trans women is incorrect in addition to being bigoted; what will happen instead is that anyone who doesn't meet the arbitrary standard, *including* people who are not trans, will be rejected, while unremarkable trans women will still be welcomed.
Heck, the woman in the article assumes she's the person in question because she doesn't know of any other trans female members of the gym, but what if she's NOT?! What if the complainer was objecting to a cis woman? I totally agree that regardless of the validity of her complaint - and I think she has zero grounds, to be clear - she was apparently creating far more of a disruption than the woman she was so upset about. Even if PF merely had a "don't upset the other members" policy, she'd be in violation. (That said, I think their actual policy is fantastic and their actions here have 100% backed up their statement of unqualified acceptance.)
Last month I went to a hockey game and shared a bathroom with someone who looked like a clean-shaven stockily built man, and statistically it was probably a cis woman (since there are butch trans women but they're quite rare compared to the overall cis female population). I didn't have a problem with it, and neither did anybody else, and we all got to pee in peace. 🙂