Agree fully with the difference between "Unfriendly" and "Posted Unfriendly."
Legally armed citizens can still Conceal Carry in an "unfriendly" establishment that does not post a sign. However, legally armed citizens can not Conceal Carry in an "unfriendly" establishment that does post a sign. This is a significant difference the app should conspicuously account for.
Can we make the distinction here between open and concealed carry?
While the statute does prohibit concealed carry:
Prohibited Conduct and Where Unlawful to Carry - Section 18.2-308.012
Section 18.2-308.01: Private property when prohibited by the owner of the property, or where posted as prohibited.
This statute refers specifically to where
concealed carry by a CHP holder is prohibited from carrying.
There does not seem to be a parallel statute for open carry, since open carry does not require any kind of "permission slip." In that case the gun-buster sign would not seem to have any force of law attached to it, even though the owner could certainly ask/demand/tell an open carrier to leave and if they refused, could summon the police and formally trespass the open carrier.
All of that being said, no responsible person here on OCDO recommends carrying, openly or concealed, into a business that is posted. We strongly suggest that they spend their money at friendly locations. To that end, 2A Friendly is (IMO) a useful application.