What do you do? Well, what do you do if your child likes to play with fire, or kick dogs, or pull the neighbor girl’s pigtail? Isn’t that a big part of parenting, teaching your kid that some behavior is inappropriate, and that they can’t do it even if they feel like they want to?
Hmm.
I'm talking about innocuous behavior, like playing with trucks, playing with Barbies, liking movies about Lego Ninjas, liking movies about princesses . . . that sort of thing. Your examples are ones of anti-social behavior, which you would correct as inappropriate because it may cause physical harm.
There's nothing inherently wrong about a little boy liking a princess movie, other than the fact that it's kind of light in the loafers.