Isn't it at all possible that having a more detached view of your own brain, and a disconnection from society causes one to be more likely to be aware of the distinction between gender and biological sex.
And therefore be more willing to go through transition, instead of being more concerned with the impact the process has on your social standing, your friendships, your relationships.
I genuinely wonder if the incidence rate of transgenderism amongst autistic folks is actual the real incidence rate in humanity, but the rest of us (I am mostly neurotypical, just ADHD, and cis-hetero) are more likely to repress any transgender thoughts or worries.