Without dismissing the anti-trans movement as a way to "conserve" VAWG and GBV resources, I would suggest that the issue really is bigger than that. TERFs believe that gender is wholly arbitrary. They believe that self-described trans people cannot know their "true" gender, because there is no such thing as innate gender. So trans people are living proof that radical feminists are wrong about, well, everything. That seems to me a good enough reason to be a TERF, if you're an RF.