My understanding is that "TERFs" are so indoctrinated in the whole muh patriarchy privilege causes ALL problems bs that they honestly believe that any male to female trans case is caused by a sexual fetish because why else would an evil parasite willingly give up their magical privilege power? Female to male trans are just viewed as poor oppressed souls who mistakenly think they can obtain magical privilege powers because of evil patriarchy rape culture programming.
Meanwhile normal people understand that not everything MUST be caused by some broad vague boogey man that can never be beaten. I really dont see why its so hard for a group that thinks men are the devil by blood to not understand why some of those devils might rather be angels also becauseof blood. In a lot of ways it validates their cause, it just undermines their original sin bs. Thankfully they are just a small fringe subset of a small fringe subset.
At this point, TERF is just a term for people who don't believe transwomen should count as women.