If you're referring to the movie, you've got startlingly little basis on which to condemn Dahl. Read the book first, please?

Also, even in the film, Wonka doesn't actually do anything to the kids. He just fails to protect them from the consequences of their own actions, every one of which he warns them against taking.

You could get him on child endangerment, hell yeah, but you'd be hard put to it to get him on abuse. And endangering children to test their character is something fictional adult good guys do all the time. Adult good guys like, f'rinstance, Batman.