Theres still a lot of snow up there as you can see in the linked story. He may have been sliding on snow most or even all the way, and that might be why hes still alive. That, and the fact he apparently didnt make it all the way into the water.
The stupid is strong with this one.
I was thinking snow, too. The area with easy access is on the South rim, so the associated caldera is north-facing.