If the theatre manager found out that he had a weapon on him in violation of theatre policy and told him to leave the theatre, did he have the right to stand his ground and refuse to move and pull out his weapon and shoot the manager forcing him to retreat to the door out??
A theatre is not your home or your car or even a public sidewalk that you might have a right to.
Your right to your seat in a theatre can be revoked by management at any time especially if you breach their No Weapons Allowed policy.
You need to rethink your argument.
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?