I feel your pain.
I have a special dark place in my heart for folks that dream up, over thought, hard to comply with and , yes, Asinine rules for other people.
I once found myself at an unfamiliar trap and skeet club, (on vacation) I paid for 3 rounds of practice trap. I unshipped my AK look a like, Saiga 20 ga. And Placed it in the rack along side all the pretty Browning o/u's. and 1100's I was immediately accosted and informed that ALL actions must be open to show safe.
I placed an empty 5 round magazine in and locked the slide back. (empty magazine must be in place to engage the last round hold open pin) This caused an immediate attack of apoplexy among all present. I was told to remove the offensive weapon from the range. (yes, it was black and the wrong gage)
Rather than starting a shouting match, I walked back to my trailer and unshipped my Ljutic space gun. I opened the bolt and put it in the rack. It got real quiet for a while, until I asked that all the over and unders have the actions opened to "show safe"...
Needless to say, after a short, sharp, discussion, I got my refund and was shown the gate.
There is never a good reason to be an asshat, yet there are people that seem to get some perverse thrill out of embarrassing or accosting other people that they consider beneath their station.
Sadly, you will never change their mind or the rules. If you have few options for places to shoot, I would suggest a change of guns or a 10 inch long, brightly colored, 3/4 inch wooden dowell.
Sorry for the rant, but after 30 years in the military, I don't suffer fools kindly.
RED