Which he is. The locker room/restroom thing is an illustration, not a reason and reducing a point on the nature of reality to a straw-man argument is evading the issue.
The fact that there is not yet an effective treatment does not change the fact or nature of a disease.

You honestly have the audacity to make this argument after how many generations of left wing mendacity with that exact same argument? Remember when abortion was only going to be in extreme cases, that no one wanted to abuse it and it was supposed to be rare? And now is going on to the tune of millions a year, so children can fit into their prom dresses, and don't need their parents' permission to do it? Remember when sex education was going to reduce the nature of teen pregnancies, and "your kids don't have to have it, so why are you so concerned how other people get the information or live their lives?" but leftwing social programs have made the subsequent explosion of venereal diseases and illegitimate births to people unprepared to shoulder the burden a massive social and financial cost to the whole country?

And most especially, and most closely related to this issue, remember when "gay rights" was not going to affect anyone, that it was not remotely our business what two consenting adults do in the privacy of their bedroom...except now people are being driven out of business, because of homosexuals trolling Christian businesses to force them to participate in their 'private, personal business', and suing for damages, claiming that a wedding cake is a civil right! Oh, it was fine for a business to refuse to write "Adolf Hitler" on the birthday cake of an innocent child with that name, but it is not all right for a business to refuse to participate in a "private" pseudo-ceremony validating an offensive practice?

And the main thesis of my post, which should not really be a difficult concept to understand, but nonetheless seems to be, since you don't remotely address the point, despite it being my subject line, is the hypocrisy and idiocy of liberals using such arguments in a array of issues, and then flying in the face of that argument whenever it suits them. There is no more scientific evidence that "transgender" is a legitimate thing, than there is of Creation. Less actually, since the existence of creation, lower case, is at least circumstantial evidence of the latter. Pathological mental compulsions are not legitimate justification to overthrow scientific evidence.

And as I pointed out, this bizarre fad is not limited to adults screwing up their own lives, it is being extended to children who are not old enough to buy tobacco or consume alcohol in public, whose parents, because people insist on treating a pack of sad freaks as a legitimate lifestyle, indulge them in this crap. A parent who serves their child alcohol in moderation and in controlled circumstances, as has been done for all of recorded human history, is suspect, subject to criminal prosecution and portrayed in entertainment media as pathetically permissive or unforgivably negligent, but that same media applauds a parent who allows a child to make the life-altering decision to permanently mutilate himself, is lauded as accepting and supportive.