The portion that I've highlighted seems to be an open ended policy. I'll explain.
If Wal*Mart's National Corp HQ has issued this as policy, but leaves it up to their store Gen Managers to handle this issue in accordance with their respective states laws, it could result in variances of individual store policies while still being in compliance with state laws. I believe that in most states, private businesses have the right to ban firearms from their premises.
So lets take three different Wallyworlds in Tennessee.
Store #1 has a progun Gen Manager. He/She elects to allow firearms to be carried (CC or OC) on the premises. Unless of course the store is located in a area that may be prodominently anti-gun, in which case he/she may have to ban firearms so as not to see sales fall off. These managers have to maintain health sales figures if they want to keep their jobs.
Store #2 has a Middle of the road Gen Manager. He/She may not allow OC in this store and mayrequire you to conceal while shopping in the store.
Store #3 has a staunch Anti-gun Gen Manager. He/She doesn't want firearms on the premises. They may not catch all the CC'ers, but the OC'ers are going to get the boot everytime they come in. Unless of course the store is located in a prodominently pro-gun area, in which case they may have to allow firearmsto keep sales up.
All three stores (not sure about #2) would seem to be in compliance of Tenn State Laws, thereby following Walmart National Corp policy.
As for posting signs prohibiting firearms in places of business,Tennessee statute states: