I never bought that whole argument of "government knows what's good for you so don't you worry your pretty little head".
Uncle Bert and Aunt Florie are grown adults, and if they are not felons and can pass the gun safety class, I don't see a reason why the government should not allow them to own a firearm for self defense. And if they want to drop acid on their time that's fine too. As long as they don't handle the guns while on acid - DUI equivalent type of laws should be in place for guns (i.e. if you are found drunk or stoned while carrying a weapon, your license will be revoked.)