I think their argument is that gender is purely a social construct that is completely different and separate from physiological sex. In which case, why is "gender affirming care" focused on interrupting healthy sexual development and mimicking the opposite sex?

"Gender has nothing to do with genitals and you're a pervert for hyper-focusing on the male genitals that your daughter will see in the locker room. Now give me fake, opposite-sex genitals or I will kill myself."