The heart of the matter is that CeCe wants to win. Her wanting to change genders may even be secondary to wanting to win, maybe not. She wants to win so bad that she has rationalized that competing against XX females as an XY woman who was born male is fair.
Picture this: two roomates at Stanford. One comes from a school where the average ACT is 34. Every family who sends their kid to this private school is rich, tuition is almost as much as Stanford. Another comes from a school where the average ACT is 18. Every family who sends their kid to this school is poor, many broken homes, many students live in group homes. Both students are fully convinced they worked harder than the other to get into Stanford.