Soooooooooo... what’s to stop someone from inventing some kind of gadget that sticks to your thumb that fits in the hole? Then the gun is right back to being fully functional. This seems silly.
Suprised no law has yet been written banning:
"that shoulder thing that goes up"!
LOL, they already have, but it is a tab you screw into the center of the button and makes it function normally. I have bought two bullet buttons, and both came with it.
In fact, they still show it with the attachable button at Rifle Gear.
http://www.riflegear.com/p-58-ar15-bullet-button.aspx