No, I don't think I do. I pointed out that the sign may or may not have legal effect on the ex-cop carrying.
In most jurisdicitons, signage does not constitute sufficient notice to a person that he is trespassing and not welcome. Until such time as the manager explicitly asks the ex-cop to leave, it may very well be that the ex-cop is completely legal.
I think you are also mistaken regarding whether the cop had a right to be at the theater. The ex-cop bought a ticket to view the movie and had an implied contract with the theater owner to do so. The shooter had every right to be in the theater at the time of the shooting.
If the shooting victim had disarmed in the ex-cop and, in the ensuing struggle, shot the ex-cop, would you deny the man protection of Stand Your Ground because he didn't have a right to be in the theater?
You've got an ex-cop who thought he was above the law.
He can break theatre policy by bringing in a weapon contrary to posted sign and then use it on another patron who didn't break that law.
That is what you are arguing for -- give it up.