Wow. What a crazy story. Thankfully he mentioned the price (or your son was savvy enough to ask) and didn't try to sucker him in and then hit him with the bill. That would have been borderline criminal and disgraceful. But, it seemed he only asked and your son rightly said no. Not sure how horrible that is even if a little rude and presumptuous? We love Nao and unless it has changed in the last year find it pretty reasonable all things considered. They have a Premier Cru Chablis we always get that is pretty cheap actually and we find the service to be great but of course it's year to year at places like that. Hopefully your story is more a one off than a new MO for Nao. Perhaps your son should be flattered that they thought he looked so "well to do"
My main question is what the heck was the bottle exactly that they would charge that price for even if he requested it and they didn't try to sell him on it? It couldn't have just been a "regular" recent vintage of Dom Perignon could it? Was it a classic vintage? That's an absolutely insane price for just a regular old bottle of Dom.