Big chain businesses USUALLY (imho) have two sets of rules; corporate policy, and the Store Manager's altered policy. All of the big chain corporations I have worked with over the years follow this setup to a degree. The store manager may or may not strictly adhere to what Corporate enacts. When I worked for Best Buy, the store manager had some of her own policies, some modified policies, and even ignored some of Corporate's policies because she didn't think they helped sell product and make the store run more smoothly.
For all we know F&F is subject to the same kind of leadership. Some people follow the rules to the "T" and some don't. If the employee's at one store are taught different, they will never know that the up&ups have a policy that says different. If the policy that is being broken/modified/unenforced/ignored blows up in their face, i.e, a BG starts shooting as is stopped by an OC'er returning fire, lawsuits will likely arise from the injured. The BG could even sue F&F for not enforcing their gun ban which resulted in them getting shot. But that all depends on if the BG lived.
Until this sort of stylized leadership information is public knowledge, we don't know for a fact. Speculation is purely that, speculation.
As Doug always says, "Believe nothing that you read or hear without verifying it yourself unless it fits your preexisting worldview."
If F&F doesn't have a posted list of all their policies for their managers/employees to search through, how can we, as customers, be expected to know them? If you OC in F&F and are asked to leave, say "Okay, I shall gladly take my money elsewhere." Problem solved.