Next time you might think about turning it around on him instead.
1 What? you want me to unholster a loaded weapon in your store?
2 Are you crazy?
3 Why wouldn't you tell her the truth, in the retail business it is the gun you don't see that comes out of a robbers pocket.
4 Perhaps you need to attend an NRA approved safety course sir, one of the first things you are taught is that there is no such thing as an unloaded gun, you never should have even asked the question.
This is how folks get KILLED. Shift that scenario a little, you unholster, rack the slide back and lock it open, pick up the cartridge, put it in your pocket, thumb the slide release, he says hey do you mind if I take a look at that I have never seen one, you hand it to him, the idiot puts his boogar hook on the trigger and BLAMMMMMM, because you neglected to drop the mag as you were huge nervous first about being addressed, second about committing a fairly unsafe act in unholstering, etc.
This might sound pretty far fetched for you, but it is not, it happens a LOT, guys clear the chamber without dropping the mag, or they lock it back and slap a mag in and ASSUME the gun is not loaded and test fire it after cleaning. I can name four folks whom have admitted doing this and none of them had any less than 20 years experience with firearms.
Like Zeke said, it never clears the holster unless your going to shoot it. If you like to clean it once a week, put it down on your cleaning bench holstered. I have two carry weapons (more but 2 I carry the most) and both are removed from the belt and put into the safe IN THE HOLSTER and back to my belt the same way.
Cops have to holster and unholster a lot and a large number of the negligent discharges happen during that process.
Next time they ask such a stupid question try "Sir, my training taught me one thing real well, there is no such thing as an unloaded weapon" When he ask about the pipe "Sir, the only way you would ever need to know that is if you threatened to kill me at which point you could verify for yourself by simply looking down the barrel and I don't think you would like to do that one." May I finish purchasing the cartridges I have on the counter without any more questioning of my legal behavior or do I have to shop some where else as a respected customer?"