HB, It appears you are reading some of what I posted, however, not sure why you bring up other issues. In the spirit of discussion I will respond to your other issues. I totally agree a person, with or without a gun, is committing trespass if they don't leave your business if asked. I also agree no one should be allowed to "do whatever they want" in your business. Good issues that may deserve further discussion but they have nothing to do with what I'm talking about.
I'm talking about a gun legally in the pocket of a patron that nobody knows even exists. And if, this patron uses that gun to thwart an attack without firing a shot. I say that just because you own the business you should have no right to a legal remedy against a patron simply because they legally have a gun and you find out and don't like it. Simply owning a business and having a gun free sign does not afford someone the right to take another person's second amendment right to self defense. I know some business owners can and do wield that kind power over the minions but I believe in this country they should have never been given that authority. I believe we should not allow any citizen to have that control over another just because they have a business. There are many advantages to owning a business just not disarming legally armed citizens.
It appears to be your position as the owner of a movie theater, with "no guns" posted at the door, you could have somebody with a gun arrested for trespass because they popped James Holmes in the head before anybody else died. I believe that attitude is exactly why these shootings happen in the first place. People believing they have the right to create a gun spree zone without any responsibility for the consequences.
You have said nothing that convinces me that you as a business owner have the authority to disarm me in your business unless I'm doing something illegal with the gun. Carrying it in my pocket is not illegal with a permit nor should it be in your business. I believe the only right a business owner has would be to see a copy of my permit if he suspects I'm armed and if I'm asked I must be truthful about possession.