Good point! In fact, I even had a conversation the other day about a trans phobic family member of mine. They were okay accepting another family member who is trans masculine, but made a point of rejecting trans women. I remember when I was a child hearing the trans phobic argument that “there had always been trans men” because under the rules patriarchy men were just considered better. So naturally “women wanted to be men.” But then under those same rules “no man gifted with manhood should ever want to be a woman” and such people who break this rule have threatened the social order.

So trans women have broken the rule or patriarchal society because they are actually women who give up male privilege to live as themselves. Thus trans masculine are deleted from the conversation.