Would people be as quick to judge Walgreens if he had been fired for carrying a machete in to work?
If he could conceal it to prevent causing a panic, then maybe it wouldn't bother me, other than the fact that it would be more of a danger to bystanders were he to start swinging it. Not very effective either, but that wasn't your point.
Do you have the right to keep me from carrying a gun on your property?
Yes.
My private property. I can keep you off of it completely if I want, for whatever reason I want. But my property isn't open to the public, which actually does make a difference in the eyes of the law. And on my property you aren't required to be there every day and you aren't required to perform a function that could easily put your life at risk. Were that so, I would not restrict your right to defend yourself.
I see where you're going with this. It's the same property rights argument that always comes out in instances such as this. The "what about your property" analogy often comes up as well, but that isn't a fair analogy. It's true that property rights, in their pure form, do allow the property owner to decide what can or cannot be taken onto the property, but those rights are not unlimited, especially when an employment relationship exists. There are many things that you could legally restrict at your home that an employer could not legally restrict from an employee. There are also things that an employer can require that you normally would not.
The issue here is whether the employer is unduly restricting the employee by placing him into a situation where his life is threatened, but not allowing him the means to protect himself. If an employer placed you into a high noise environment without ear protection, they'd get sued. A high dust environment without dust masks, high radiation environment, etc., etc. The argument being made is that crime, and in this particular case crime against pharmacies by addicts, is of such a nature that it has reached the level of being an occupational hazard, and that restrictions against drug store employees being able to carry firearms for protection thus represents an undue hazard for said employees. I personally doubt that argument will prevail in this case but it's one that is coming up more and more in recent years, so it may find a sympathetic ear in our courts not too far down the road. I'd sure like to see it.
But you do bring up a good point. As things stand in our legal system right now, property rights are probably in Walgreens' favor.