I certainly would not imply travelling lite was at fault here. I know from my own experiences climbing, that light and fast is the safest way to climb many mountains and/or routes. That is not to say a light pack causes accidents/deaths. It can be a contributing factor. The circumstances can overcome the best laid plans.

I am sad to hear a fellow mountaineer has lost his life doing something he loved. I know most of us are only speculating, perhaps in our struggle to try to understand how this could happen. I have never felt cold enough that I could not carry on, slow maybe but not a total halt. I can only guess that there is some other cause in this instance, altitude sickness or something else that would take all your energy. I know I have been ill on Ranier and was until I got down below 10K. To climb down Liberty Ridge would not likely be possible with a serious illness. It is not an easy task on a perfect day with a fully energized climber.