Possibly unarming yourself then having a chat with the manager can accomplish one of two things.
1. They become aware of the law and post a proper sign.
2. They need your business and take the sign down. Many signs were put up with no thought and have lived quiet unnoticed existances for years and need the owners to review their stand.
either way they become compliant and you know where you stand without being cuffed and dragged. To me it's not important as I defend their rights as much as I defend mine.
