That is a really sad story.
I don't know what the circumstances were surrounding his fall, but it just seems like the easiest lessons are the hardest to learn sometimes. I've been hunting from tree stands for years, and other than always wearing a harness, I've never really thought about the ramifications of falling out of a tree until this year. It's serious business and as this story painfully illustrates, not planning for a fall could be the worst, and last mistake you make.
In addition to hunting, I also enjoy riding motorcycles. There is a saying: "dress for the crash, not the ride"... I think this applies to hunting from a tree stand, too.