Posting Property Doesn't Change Insurance Rates or Libility
I have talked to an Insurance Agency that sells Commercial Property Insurance in Ohio and West Virginia. They represent over 20 different Insurance Companies. They have never seen a policy or heard of any policy that required or gave reduced rates to any business that posted their property. They have never seen a policy that stated they had to post their property. I know this agent very well as they went through my class to obtain a Permit to Carry in West Virginia and the agent has been selling insurance for 20+ years.
They did tell me that there would be a surcharge on a policy if the owner kept a weapon on the property. So if a business keeps a firearm or any weapon on their property they will pay a surcharge but there is no savings of any kind or limits to their liability for posting their property. The surcharge pertains to all weapons. They even told me about one establishment that kept a big sword on the property and had to pay the surcharge.
So if a company tells you they have to post for insurance reasons they are just trying to pass the buck and say they have to. Ask for the name of their insurance company if they state that and I bet they will not tell you.