Just a thought, could the kid have been laughing loudly during the "non-funny" portions of the film? Just as if somebody was talking loudly during the movie.
Some people may have complained of the disturbance. Only stupid thing was the manager saying the kid had to leave but the family could stay. that's just wrong.
They got their money back... move on, people.
I wondered about that too. If an autistic or Tourette's Syndrome child is bursting into laughter at points in a movie where that's totally inappropriate, the rest of the theater hears the laughter but has no way of knowing it's coming from a disabled child. It could really ruin normal people's enjoyment of a movie, to hear loud laughter at points where, for example (guessing at the content of this movie), a mother penguin has just realized that her baby is dead.