I don't know if I'd say transhumanism is "popular" among the autistic nerd population, but it's probably more popular than it is among the population at large. And trannies can definitely be seen as a step along that path.

In my early 20s I found transhumanism very appealing and treated my humanity almost as a defect to be overcome, and it wasn't until I became a bit older that I realized my humanity was simply a part of who I was and that it was foolish to treat such a significant aspect of myself as a "defect".

I'm sure there are people who never reach that second stage.