Since the bad guys choose the place where they strike, you need to have your sidearm with you wherever you go. Lots of businesses in 'nice' neighborhoods get robbed. Some of the innocents get killed during the robberies. I prefer not to be one of them.
May I suggest Daveloneranger's armed citizen ping list? You'd be surprised.
Well, I suppose so, but statistically the chances of that are so small it seems ridiculous to me.
It is entirely within Costco's rights to ban guns, or smoking, or any other activity within their stores. Customers can choose to patronize them or not in response to their policy.
It sounds as if this individual has made his choice, as is his right.