People don't stop being trans because you disagree with them politically. I despise Jenner and other high profile trans grifters but I'm not shitty enough to deny their identities.
Do better. As a user of both sites this shit is genuinely upsetting. Despite how you may feel about hexbear, how can you claim that they bait people into revealing their internalized transphobia and then turn around and make shitty claims like this? I don't give a shit if you call me a tankie or red fash or whatever, but I'm trans whether you like me or not.
Gatekeeping other people's identity is unacceptable. The defederation almost occurred in part because of the dismissal of a users identity. It doesn't magically become acceptable when we do it.
Do not gatekeep other folks identity.
End of story