Obviously no school is going to deny a transgender teen to flip identities considering that they know dam well that denying them is discrimination, especially for a transgender teen. The reason has got to be related to the scenario where, lets say, a gay male decides to flip identities because he felt he should have been born a girl.
Where does the school draw the line? Though, imo, we cannot compare a transgender to a gay male desiring to be female and therefore the line should be drawn in-between.
I'm not sure what you're talking about but I'm positive that has nothing to do with this.