How obtuse of you. It runs deeper than that and if you honestly think a ten year old kid wants to change genders to get a leg up on the competition then you are sadly mistaken.
I played ball with a young woman who was a kick ass pitcher at 7 years old. She could hit too. Most of the time she was the only girl on the field and nobody even noticed until she started to blossom. She is still one of my close friends along with her wife and went on to a semi-respectable pro softball career.
We always get a kick out of reminiscing because she could strike a lot of young dudes out but I always could hit her around the park. Why? Because we played together off the field and I knew exactly what she was going to throw at me. Other dudes went into the box thinking that "it's a girl" and whiff away at the salad she tossed. I didn't have a big arm either but I was pretty successful working with her on some crazy overhand pitches like Whitey Ford type of stuff.
She's a tough 'ol gal and I always rib her that she should have been a linebacker because she could certainly smoke me to this day because she knows exactly where I'm gonna cut.
We just played man. Nobody gave a rats ass about where you went to the toilet, we certainly didn't have naked locker room parties until we got to high school and even then it was completely optional.
Just think of what it would be like if you're a young kid and don't think you fit in your own body. It's really hard for those kids because of assholes like you. They get beat up and traumatized for no reason and eventually are left with no place on earth they can live. They are forced to think that they are an aberration, a freak, a subhuman.
If you want to think that they would go through all that for a medal at a swimming meet then I have some news for you. You're wrong.