The "I am still a transhumanist" here might be another example of that; possibly more high-profile due to being part of the Fun Theory sequence.

You seem to be taking a statement of the form (to my reading):

"X appears to imply Y, but it doesn't (assertion). In fact, Y is false (separate assertion)."

and reading it as:

"X appears to imply Y, but I'm a Y-disbeliever (premise). Therefore, Y is false (inference from premise)."

Basically, it seems like you're reading "I'm a transhumanist" as a statement about InquilineKea from which they fallaciously draw a conclusion about reality, while I'm reading it as a disguised direct statement about reality, semantically equivalent to "pursuing the right technologies has positive expected value" (or whatever).

A more charitable interpretation of your post is that you're arguing against belief-as-identity in general, and using "I'm a transhumanist" as an example of it, but if so that's not clear to me.