To be very, very frank with you, I have doubts about that they were as well prepared as he states them to be. It isn't true that there are conditions you just can't survive (except lava and similar very extreme stuff).
If they had a shovel and dug themselves a cave and had appropriate clothing etc. chances are they would still be alive.
Not trying to be distasteful here, but people want to justify their actions after such an event, to themselves and others. It is neccesary in order to keep your sanity. The conclusions can be wrong, they are self-theraputic, not survival tips.