“Trans-exclusionary radical feminist” sounds pretty pejorative, most especially the “radical” part.
It is a real branch inside feminism, which lots of women identify with, and it doesn't mean what most people think it does.
Men were all inherently bad, penis-in-vagina sex was inherently rape, lesbians were good, trans-women were infiltrators and trans-men deserters.
It's only pejorative in the sense that it attempts to accurately describe the motives of a set of individuals who aren't comfortable with the way those motives are widely regarded. In that sense it's about as pejorative as "racist".
It might be loaded with denotation outside of the scientific community, but the word “radical” has some various scientific meanings, as other commenters have noted.