Every range I have been to has had a rule that guns are to remain cased/holstered until on the line.
The range I go to downtown is run by ex-cops and I do believe they would of drawn and possibly fired at some idiot taking his gun out in the lobby.
A person only has 2 reasons for taking a firearm out in the lobby of a store/range:
A) they are planning to rob the place
B) they are a moron
Even if the gun is unloaded no one around you knows that. I do hope they at least kicked the guy out right?