I was actually at the store when this happened when you were interacting with the guy at the counter. The rule is that the actions must be open if not holstered or bagged. This is for safety reasons and it allows everyone on the range to see clearly that the gun can't be fired. It isn't something they do to be "turds" or that they are "unknowledgeable". It is for the safety and peace of mind for the customers. If you think you can't follow a simple rule, then it probably is best that you shoot elsewhere.
They need not worry about me and their rules. I will shoot elsewhere. Safety and peace of mind for the customer you say? Renting a gun that is then used to kill an individual is probably more destructive to safety and peace of mind to the customer, but what do I know. There are to many other places not infested with the turd mentality of this range. And I was told it would startle people to see a gun not in a case at a gun range not the drivel you spoke about.