They hung up on you probably because they assumed you were some kind of journalist looking for a soundbite so you get a recording of them agreeing with you that he's a man, and then could turn it around and claim how "TrAnSpHoBiC" it all is. They probably agree with you but are actively trying to control their messaging to avoid this sort of threat where someone calls in trying to manufacture a controversy.

This is also what makes it difficult to have any discussion even on the opposite end of the political spectrum; any legitimate criticism like "hey maybe their death threats to women are bad" are viewed as literal bigotry. None may step out of line on trans issues lest they be labelled right-wing, regardless of actual political leanings.