When you open a business to the public, you do lose some of your property rights; a business open to the public is NOT like a private home, especially when it's a publicly held corporation.
A person can ban - from their home! - someone else for ANY reason, or no reason at all. Race, religion, sexual orientation, the way a person parts their hair, speaking with a funny accent - are ALL reasons a person can refuse to admit someone to their home.
However, a business ostensibly open to the public like an ordinary restaurant, department store, or supermarket can't (for example) hang up a sign saying "NO COLOREDS ALLOWED" or put up a job recruitment sign saying "No Irish need apply." Simply by being open to the public, they are likely compelled by law to also provide fire protection, emergency egress, ADA compliant facilities, etc., in their business, whether they want to or not.
Now, you may plausibly argue from a property rights standpoint that they SHOULD be able to have discriminatory policies and skip public safety rules in their businesses, but in today's legal climate . . . they can't.
So with this background, it's reasonable to hold a business that bans guns legally carried for self protection as recognized and approved by the state while at the same time failing to provide protection, OUGHT to be held liable, since it is reasonably foreseeable that their ban endangers the safety of persons who would otherwise take responsibility for their own safety.