Adkins asserts that being transgender is not a mental disorder, but simply “a normal developmental variation.”

Normal, or rather, regular variations don't need treatment. I'll die on that hill. Thank you, very much. Juxtapose this by going back one hundred years in medical technology. Could we maintain that there are transsexuals that are of a "normal developmental variation," for which we did not yet have the requisite technology and thus refused for treatment? Not that the outcomes, today, are particularly pleasant. Of course, the counterexample to that thought process is all of modern medical technology that can say, save someone from brain cancer. It couldn't one hundred years ago. But that rather refutes the idea of "normal developmental variation." It's a matter of health and distress, no?

I've not yet come to a personal, satisfactory conclusion about what does and does not constitute mental disorder. It's a rather complex philosophical topic, in my mind. But one thing has always stood out for me: being in-touch with reality. There are other proposed criteria that, on their own, or in tandem, could constitute mental disorder, but I'm rather fond of this one. Or, in other words, schizophrenia with its delusions could never evade the definition. So that puts people--consider for the sake of argument just adults--with cross-sex wishes into one of two categories. Those that understand they are possessed of something atypical, and those that really do think they're "trapped in the wrong body." One constitutes mentally disordered, the other does not. Even though the aetiology may be the same.

A priori it strikes me as rather odd that we are just now, as a whole, becoming aware of this "normal developmental variation." Not that I can't trace various forms of transsexualism through a few centuries of history. It was just quite uncommon. Quite a change to become the zeitgeist--a proxy of the on-going "culture war."

The author is hitting on the recent methodology of trans activism--throw shit at the wall and see what sticks. It wasn't long ago that the postmodern claim in this camp--that sex isn't real--was quickly dashed. If sex isn't real, then what are you transitioning from and to? This incoherence was even too much for them. Or, perhaps, it was not pleasing.

Why accept transgender “reality,” but not trans-racial, trans-species, and trans-abled reality?

All very real phenomena. But, I think I digress is some regards, because I can empirically measure the aforementioned. And in some regards collect psychophysiological measurements. Transsexual, transracial, transpecies, and transabled. Real things, certainly, but I do reject the respective claims that person "really is who they say they are." I'll regard a person who desires to be an anthropomorphic animal as a person who wants to be an anthropomorphic animal. Not that they really are a wolf. Obviously.

I wouldn't even say this is a compromise. It's taking things as they are. I have no intent of ignoring and denying that people with authentic, life-long, cross-sex desire exist (not so far away in terms from plain-old heterosexuality; but we were talking about transexualism...) We can have transsexuals without the attendant demands that they really are the opposite sex, and we can reasonably accommodate them. Society thrives on polite fictions, but it will fail in unconditional fiction. (Because there are people possessed of atypical sexuality that results in these outcomes.) We don't tell schizophrenics that the voices in their heads are in fact, real. That would be doing them a terrible disservice. It's likewise not a kindness to participate in the lie that the transexual wants to tell themselves.

You've noticed the complete lack of solipsism. It's not just enough that the transexual believes. You have to profess your fealty as well.