Basically this. It's not like it's a big huge expense for the place to accommodate herhim.
FTFY.
Expense doesn't matter. If it has a Y chromosome it's a dude and it should use the mens restroom. Double that sentiment if they haven't had their cock chopped off. And the owners have every right to enforce such a policy in the interest of their actual female patrons who are, rightly, uncomfortable sharing a toilet with little miss freak show. If ol' Buffalo Bill doesn't like it let him take it down the street to an establishment that caters to that sort of thing.
Add to that, if little miss freak show didn't make a spectacle of itself in the ladies room MAYBE NO ONE WOULD KNOW THE *expletive deleted*ing DIFFERENCE and we wouldn't be having this lovely little chat. Seriously. If miss "Norma" had closed the stall door, sat there like a good little lady whilst doing the deed, and kept her cock to herself maybe the other ladies wouldn't have called him on it and said GTFO. Instead he stood there with the door open, hiked up the mini skirt, rocked out with his wang out, and took a nice long manly piss in the ladies room.