And that is a Bull excuse. Perhaps I can see it on duty... but if you are off duty you are not their responsibility nor can they be liable for your actions.
No bull. If you have employees carrying guns, and you are aware of it and authorize it, your insurance company will have a fit. There is no doubt about it, your premiums will go up. You might even have to go back to the table with negotiations to get a new insurance plan. Its an expensive thing. Most places are in the business of making money, and shoving it down the barrel of your cashier's pistol is not prudent.
Off duty, you're right. The liability claim doesn't fit. However, you now have a question of reputation and image. If an off-duty employee is strapping, concealed or otherwise, and their sidearm is spotted by a regular customer, on- or off-duty, on or off premises, and that regular customer is not friendly to firearms... well, you've got a problem. And it isn't a problem they'll like. With today's brands being multi-million dollar assets cultivated over decades or centuries, most companies won't want to be the brand that has guns crawling throughout their stores.
EDIT: Starbucks is a good example. They are adamant about their gun policy. They allow carry to the extent that state law allows it. If you turn around and say Starbucks is pro-gun, they'll stop you and say NO. We follow the law, we take no position on gun rights. And for the same reason, they worry about their brand.
Now, you can make whatever argument you like, but it comes down to simple dollars and cents, and its not picking on guns. I work in politics, and I can't tell you how many times I've seen the biggest, fiercest, staunchest Republicans refuse to put political signs in front of their homes or businesses because they worry about losing business. No matter how absurd it seems to me and you, it is a real, valid fear.
