There is a difference between selectively presenting true evidence (or at least evidence they believe to be true) and telling things you know to be false.

Wasn't he basically just saying that these kinds of statements radically lower his epistemic confidence in empirical claims the movement makes which are politically convenient?

Once your cause has embraced the dark arts how can you be sure what you're doing is actually saving people from hurting? Are you sure the evidence for this belief, or the evidence that convinced you to join that cause in the first place wasn't just another 'pious lie'?

The interesting question is what measures will pay off best in the long run.

Actually lying about the science might blow up later. On the other hand, saying that we don't know what causes gender dysmorphia, but it begins very young, is not a matter of choice, and gets relieved by living as the gender that feels right to the dysmorphic person-- and living in that way is not harmful-- is harder to say forcefully than to say "born that way".

We're willing to do any damn thing to find a sense of closure, of vindication. We don't actually care to reduce evil, since we're subconsciously quite aware that it would require us to take unacceptable measures.
To enforce a ruthless order and violate the sanctity of the individual, to disarm the weak and make them submit to their fate. Many here have been hinting darkly at this for a long time.
The reactionaries are completely correct in their bleak worldview. There is no deliverance. Good intentions are a self-righteous delusion, in a sense. Suffering can only be minimized by monstrous and inhuman policies. Someone will always scream and scream behind locks, walls and chains, behind a facade of normality. Finding happiness in slavery is the best that most people can count on.

...For fuck's sake, donate to SIAI.

... because you don't, as a rule, choose your own neurophysiology. Certain structures in transsexuals' brains are closer to the form they take in cisgendered members of the sex they identify with than the sex they appear to be.

Autism is a choice!

Then you are perpetuating cissexism.

... how so?

there is no brain scan for trans

The fact that we cannot currently diagnose gender dysphoria [EDIT: in a living subject] with a brain scan does not change the fact that it is caused by a neurological disorder, and as such is biological, not a choice.

if you experience yourself as trans and the scan says "nope" it's the scan that's wrong. The individual is the sole authority and the diagnosis is by telling a shrink what you experience.

Are you saying that cisgendered people should be eligible for gender reassignment surgery and so on, or that any brain-scan based test will be imperfect?