Not agreeing with someones ideas in a given topic, doesn't mean that person is Transphobic. It would be like calling a Trans Person Heterophobic. It's a slur, basically name calling.
Transphobic is a buzzword generated to try and make people seem like lesser people. Like they are afraid. It then also was created to empower those that are Trans - because then folks are afraid of the trans person.
I'd estimate that only maybe 2-3% of people that get labeled Transphobic are actually Transphobic. Name calling isn't nice 🤠