The thing you have to understand about TERF ideology is that they think:
- Men are evil rapists
- Women are dainty weak little waifs
- And, of course, gender is immutably determined by sex assigned at birth
So naturally they think trans women are evil rapey men trying to infiltrate women's spaces, while trans men are weak-willed stupid little girls who've been seduced into Gender and don't know any better.
Very feminist, much radical.