Not really answering here, just adding a few things the OP may not have considered - pro and con.
1) A calm demeaner means jack [color=#FF0000]█[/color][color=#FF0000]█[/color][color=#FF0000]█[/color][color=#FF0000]█[/color][color=#FF0000]█[/color]. He's most likely bipolar, and about to go into a different mode when his brain chemistry changes (the reality of seeing the money, and realizing he now needs to get out of the store).
2) He has the drop on you - big time! If you're CC'ing, good luck getting out your weapon under that kind of stress.
3) I
may not be CC'ing. If I'm running a jewelry or similar store, I'm in a shirt and tie. Not easy to conceal a usefull weapon (there "may or may not be" one under the counter already pointed in his direction though).
If it's my business, on my property, I
may have the option to OC, but probably would not as this makes quite a telegraph, and might scare away the lady buying a Rolex for her hubby, and the 12 K earrings. I figure that gun store owners OC because they are obviously armed. Depends on the business. A lawn mower store is a different ballgame.
4) If he doesn't know he's on camera, he's more of a nut than you're giving him credit for.
5) I seriously doubt I'm going to try to hold him in an environment that can change at any moment (customer enters, etc)
So, Overall, I'd PROBABLY not give him a second chance if he made the mistake of giving me the time I needed.
I used to frequent a gas station at which the booth was bullet proof glass. It had a break-away lever inside, and a LOADED shotgun at an angle just over the average Joe's head. One step on a pedal, and one quick pull, and a 12 GA Mossy was saying "HELLO"at your face. I knew the guy enough for him to show me the system.