There is no name calling involved in calling a bigot a bigot. The whole “polite discussion” thing is at best a thin veneer of respectability slapped on an obvious dog whistle.
Free speech does not mean freedom of consequence and it is well within Nexus Mods’s rights to not tolerate transphobia on their platform. I would even call that the bare minimum, actually.
If OP really wants honest and constructive discourse they should come out and actually express an opinion instead of hiding behind the fallacy of having “constructive” Interactions about whether or not fascism is ok.