> I don't think having her son take ballet classes is forcing anything on him

It's her idea right? And did he show any vague interest in dancing in any form for her to decide he might be interested in ballet? And can he just stop if he decides he doesn't like it?

No, it sounds like he is in ballet to satisfy her fears about her son being too masculine. Maybe he'll take the hint and turn out to be gay. (Sorry, couldn't resist.)