This is a good find, and a good fight Dan. I hope you will see it through. A cave is not a building. This is a prime example of someone or some organization trying to hide behind a law or definition, or to try to twist the words thereof into what they are not, in order to subvert the constitutional rights of the people, and trying to create a PFZ where there is none.
The safety of the employees is dependent upon the people retaining their rights to self defense. Once again, an example of backwards thinking. Perhaps they have been in the cave too long?