what??? On duty don’t count??
1) Nope. "No guns" means "No guns". Learn to live with it.
2) He wasn't "on duty" as a government employee.
3) As Citizens, we're never "off duty".
No, it doesn't -- unless he was actively investigating a crime or acting in "exigent circumstances".
If he was simply on break, a property owner has a right to exclude police from the premises, with or without guns -- just like they can exclude you and me.
It's a stupid thing to do, and anyone that does it is subject to criticism, and even responsibility if something bad happens. But, it's their choice.