Consider the liability following such an invitation enabled by an entity with no membership control.
Who would be liable for an incident involving an openly carried weapon? Who would be liable for an incident involving a weapon openly carried by a member of the sponsor of the signage?
Choice carry doesn't have many membership controls either. ( except for no felons, age restrictions ) Would the state be liable?
We all can be sued for just about anything these days. On one hand we advocate choice carry. We have a list of businesses on another thread that won't let people OC. WCI is involved in several lawsuits. Then we discover we could be sued if we try to protect ourselves with the same weopons that we advocate to have in our possession.
There are risks in everything we do.