If a multi billion dollar corporation knowingly allows employees on the clock to carry firearms, that corporation will be liable for anything that employee does with their gun while on the clock. If the employee has extra training and is employed as a security guard, then you can insure against that risk....but standard employees would not qualify for liability coverage for that risk. Not saying I agree, but that is the reality in which we all operate.
I was told WalMart has a no firearm rule for employees..... not permitted in their personal vehicles on Store property. Violators will be fired.
I am not sure if this is fact or not, but it is a CYA that has to be in place. If something does go wrong lawyers today will attack the fine print and find fault with the wording if it were ambiguous in anyway.
Phil