He does it, after you beat the game and do a second playthrough with the fat drake cheat.I thought they were using GPU physics to calculate the ring getting stuck.
Kidding aside (if that's what you think I thought?!), someone who is constantly climbing and clinging onto things wouldn't wear a ring. He could as well wear an inflatable sumo wrestler costume because it's a game and stuffs and Drake is not real.
edit: This belongs in the UC4 thread, sorry for the noise.