Is it normal that she makes fun of other people's choices?

My 18 year old nephew, who was born as a niece, is transsexual. It really gets to me that when someone accidentally calls him a she, he gets angry and acts out, yet he calls my other niece lesbian (my other niece is not lesbian, she is bi).

In another instance of her behavior, she-he was watching American Football today, and after the game there was a figure skating show on. I like Figure Skating and Gymnastics, but they are far from my favorite sports, which are boxing and basketball. He-she started saying that I was "gay" for watching a "woman' sport! Not minding that he-she is still a woman and had watched Football, a "manly" sport and that I could have said something about that too.

Is this behavior normal of women-to men TS children or is it just her? And should her family talk to her about her behavior or not and if we did how should we approach the subject?