Sparky... there is nothing in the criminal code that says the police will enforce a policy of a private organization (which is what a no firearms allowed sign on private property is) ... holy hell just read the code. It is even in English for you, Section 3503.
https://www.legis.state.pa.us/WU01/LI/LI/CT/HTM/18/00.035.003.000..HTM
Your beloved signs do not quifiy under 3503(b). Firearms are not mentioned.
While you are at it find someone that has been charged with the crime that you say is so offensive. Put a link to the police blotter.
If you were to SEE a firearm in a place where your sign was posted and called the police, they would just ask the person to leave or remove their firearm from the premises. They are not pressing charges for a crime unless the person then refused to leave. That is only after you specifally had asked them to leave after seeing the firearm (not just 80% of the time I can tell people that carry from ones that do not). Again, you would not know they were carrying until you saw something. And back to my very first point, for me the bullets would have already been fired. And even then, while cleaning up the mess, you would need to then ask me to leave the premises for not following your policy (BTW, I would still stay for the police report).
If you had a policy that red underware was prohibited in your establishment and a sign at the door that stated such, do you really think that would be enforced as trespassing by the police if someone wore red underware into you establisment? There is no law being broken by wearing red underware (just like there is no law being broken by CCP). And how would you even know if someone had red underware on unless they allowed you to see it?
Simply not following a written/posted policy for a private establishment is not trespassing.
It looks like you have a novel legal theory.