I don't believe the APA is on your side with this one. Transgender people were taken off the DSM in 2012, just as homosexuality was taken off in 1973. At this point I would say the people describing transexuality as a mental illness are more along the fringes of the profession, or like the hack that wrote that federalist rag, completely unqualified to speculate.
You are either being disingenuous or you are incorrect; it was not taken off, it was renamed Gender Dysphoria instead of Gender Identity Disorder, and there was a shift from trying to correct the "incongruence" between birth (actual) gender and "identified" gender, to trying to correct the "distress felt" from having an incongruence between birth (actual) gender and identified gender.
Homosexuality was removed because preference is like opinion; it's not crazy to think chocolate is better than vanilla.
The DSM still recognizes that there is a gap in perception and reality for transgender people (this is practically the definition of mental disorder, when you don't have a grasp on reality); political winds have shifted to focus on pacifying this minority with self-justification instead of "judgmental" treatment largely because of the power of the gay rights movement. Specifically, it was heavily lobbied by LGBT activists citing that there were communities of people "living between the two binary genders who were not seeking psychiatric treatment."
Well golly.
There are probably a ton of schizphrenic people out there not seeking treatment too. Doesn't mean that they are experiencing reality just because they aren't bothered by their delusion.
Anyway, you'll still find Gender Dysphoria in the DSM though, because, well, it's delusion. People like the ones who took it out of the DSM did so because they were afraid of hurting feelings, not because there wasn't a gap between perception and reality. The entire basis for removing it is based on the concept that there is actually a space between genders, which, uh, is really only scientifically debateable if you are talking about mental states to begin with, since there is no room for debate at all on the fact that chromosomes are either one set or the other.
As far as anyone being a "hack" -- let's just say your biases render you completely unreliable in determining who is and isn't a hack with any amount of credibility. And if you think the DSM can't be politicized, think again.