First, the young man should have been forced to turn away and face the wall until the "accommodations" were resolved. Bad parents would fail to do this.
Second, if there was ANY reason for him to be there (accident, surgery, handicap, emergency, etc), at any of the places we've been, not only would any of the men be more than willing to vacate the men's room, we would have gladly stood at the door until they were finished.
We attend festivals, craft shows, stuff like that, which often overwhelms the facilities. In urgent situations, we've helped coordinate a "switching use" of the men's room when the ladies room line got too long.
There are ways to handle these situations, but FORCING anyone to be ogled is NOT acceptable under any circumstances.
Of course, if the mother simply slapped a skirt on him, he can apparently go into the ladies room and ogle whomever he wants any time he wants and the police can be called to FORCE YOU to LET HIM!
Forced to accept ogling