From the original post:
"Costco does not believe that it is necessary for firearms to be brought into its warehouse stores, except in the case of authorized law enforcement officers. For the protection of all our members and employees, we feel this is a reasonable and prudent precaution to ensure a pleasant shopping experience and safe workplace. Our policy is meant to protect our members and employees in all warehouses around the world. This is not a new policy and we do not customize the policy for each individual city/county/state/country where we do business."
I do not believe that it is necessary to have the same belief as Costco on this, so we each retain the right to our beliefs and move on. They didn't forbid anything, the entity just shared its belief with everyone else. Concealed means concealed, so they have no idea if someone entering shares their belief on the topic.