Googled it right after your post correcting me. I'm going to have to get a copy because it was a fascinating documentary, and the footage of the crevasse (sorry about my crevice blunder) was really effective and powerful. Simpson's (he was the guy that was left, right?) climb down that mountain is the stuff of legends, only it's true. I wouldn't want to be the 'rope cutter' that's for sure. But I have to say that I really didn't judge the guy too harshly myself when I first saw the piece because it didn't seem he had much of a choice. I don't see how he could have helped Simpson, really, and if he hadn't cut the rope he might have caused the both of them to die. What do you think his chances of saving the both of them would have been should he have stuck around?
Once Simon lowered Joe off that precipice, there was no other choice. He couldn't pull Joe up. Joe couldn't pull himself up. There was nothing solid to anchor Joe to, and Simon's snow seat kept breaking down in the soft powder, jerking him toward the precipice. Had Simon been able to hold on to Joe through the night, he still would have been hard-pressed to get him over to the place where he was able to come down the next morning.
You could also probably make a case that spending the night in the relatively sheltered crevasse was better for Joe than spending it dangling out in the wind and snow.