Is this a case of "topping off the tank" or forcing more fuel into the vehicle after the pump has clicked off. The auto stop of the pump means the gas has reached the tip of the dispenser nozzle. It's a safety feature to prevent accidental overflow, which is unwanted for several obvious reasons.
I'm not totally taking Hyundai's side because no vehicle should simply shut off while driving because of this, but I do think there's a degree of user error here when it comes to misusing a system and overriding the pump's safety feature.
I agree that topping off the gas is not a good practice. I don't do it, not sure if my wife has been or not. That being said, millions of people top off their gas every day, for whatever reason. Regardless of the extra minute amount of fuel being pumped in, there's no reason my car or any car should be stalling like that. Maybe it was the parts that were failing, who knows. But for the dealer to insinuate that topping off my gas tank every now and then would cause an extreme safety issue like this is just beyond ridiculous.