Parents enroll their unwilling children in all sorts of programs - sports, music & dance - in an effort to expand the young mind and body.   How many kids do you remember that liked practicing piano?  Not every boy enjoys hockey.  This is a parents domain and using the term "force" to describe this is offensive to all parents. 

I suggest that the potential skill acquisition far outweighs the possibility of any mental setback from this boy taking ballet.  At the least, he may learn to walk with some grace.