We need financial and civil liability insurance reform.
Ban, as unreasonable, all clauses of all insurance contracts making employers responsible vis-a-vis employee uses (or misuses) of firearms on company property, irrespective of company policy, explicit or implicit. Then, there can be no excuse of "It's not that we, here at BigCo, are antigun. You see, it's these evil insurance companies that insist on writing liability insurance policies for our company that demand we ban all guns from the workplace for any reason, and we just can't afford to write that liability out for the additional premiums they would charge us. Maximizing shareholder profit, don'tchaknow?" goes right out the window.
Then, if Kroger doesn't enforce its "company policy" against this guy and another Kroger employee decides that THEY should do that, but do it irresponsibly, and that employee kills a customer criminally, then Kroger can't be held civilly or financially liable, as that liability rests solely with the irresponsible employee alone.