You think there's a lot of people who wouldn't want a cross-dresser in their church, but would allow their sons to wear dresses?
Perhaps in some very conservative societies.
Where I live I'm confident that a boy who enthusiastically engages in things which actually interest him is at a social advantage over boys who halfheartedly pretend to enjoy in whatever his parents think is normal.
Ballet, for sure. Maybe not dresses so much, at least not if he is doing the wearing, but having an interest in the clothes of his female peers certainly isn't any kind of social problem.