people ideologically aligned with some form of gender-abolition adjacent movement
Political alignments do not need to make sense (it is enough if both sides oppose the same enemy, even if they kinda disagree with each other), but it seems to me that insisting that you are a different gender is incompatible with insisting that genders do not exist.
More crudely, compare the “female brain in a male body” meme and “there is no such thing as a female and male brain, the only differences between men and women are their secondary sex characteristics, and socialization”. Could both somehow be true in the same world? I don’t see how.
(That’s basically the conflict between the trans-positive feminists and the traditional feminists a.k.a. TERFs.)
I wonder if some kind of rebranding might help. For example, instead of “life extension” let’s call it “youth extension”, and make the pitch something like: people are already living longer, let’s keep them young for longer.
This could be less controversial, because instead of discussing pros and cons of immortality (which are not even relevant yet, and can get you in trouble with all kinds of people, not just religious) we will simply suggest that people get more healthy and youthful, which seems like everyone would agree with.