I'd do require more to "be on the list" than just posting a "no guns" sign. That's just avoiding tort liability. There are all kinds of signs on store doors like "no solicitors", which are there for a legal reason that have little to do with stores ideology. For example, "no solicitors" is on the doors because the National Labor Relations Board ruling in Union law, ages ago, said that a place of business couldn't prohibit protestors from blocking their doors if they didn't have a long "standing policy against allowing any solicitation" on their property. It's just about being legally able to eject agitators. So too, I imagine a corporate lawyer has told a lot of places that they need to post a "no guns allowed" sign, so that if there is a shootout of any kind on their property, a creative person can't find a tort lawyer to sue the business instead of the shooter (looking for deeper pockets). To be on "the list", perhaps there should be some record of them actually being hostile to a gun owner, or contributing to the anti-gun movement. Otherwise they may just be trying to cover their rear end from a frivolous lawsuit.