The theater that requires people that go there be disarmed cannot plausibly be accountable for providing security?
The flaw in that argument is that the theatre did not require anyone to go there. When a business promotes its “gun free” policy, patrons are warned that self-defense is not allowed there. They have the choice to waste their $20 elsewhere.
If these people had concealed carry permits and couldn’t carry into the theater they would have a case, but this suit had nothing to do with that. They said that the theater didn’t have adequate security. Expecting every business to have enough armed security to stop a terror attack is ludicrous.