Would it be gay to send my son for ballet?

I don't think it is. I think male dancers, be it ballet or any other types, are both graceful yet strong at the same time. Dancing often requires the male dancer to lift the female dancer, and also makes use of a lot of core muscles. That being said, you do have to prepare your child for the stereotype associated with being a male dancer. He may still be on the receiving end of some teasing from his peers. However, as long as he is enjoying it, and you are there to encourage him, I'm sure he will do fine without being affected by the stereotype. Just my two cents..