So the gun is just there for show?Driver's license is about permission to operate a car in public, not to own a car.
Everyone is free to own as many cars as they want with no inspections. Only if you want to take them out in public is any sort of inspection needed and that only in some areas.
He's talking out his ass. I have in the past tried to buy a car without a license and subsequently told to pound sand. Many states require a license to purchase a car.
You'll need a license for a test drive. You'll need a license to drive it off the lot. Unless you pay by wire transfer (and is your average dealer even set up for wire transfer payments?) you'll need ID of some sort. In general a car dealer isn't going to have a special procedure to sell a car without a license as it would be so unusual for them. That doesn't mean the law requires it.