The police were called for trespass after the patron(s) refused to leave for violating the rules. There’s a difference.
Hanging around in the foyer to try and argue the point is not leaving.
Obviously it was excessive, but they’re still within their rights to have someone removed.
It’s like this in Australia, too. Sometimes cinemas here have a couple of arcade machines off to the side in the foyer, but that’s about it.