Thanks for the link. Some very interesting details in there.

So he did this at night, while his wife was asleep? That hadn't been reported before. It begs some new questions about the string of bad/naive decisions. I wonder how much fatigue and get-there-itis played into this. I also wonder if a second pair of eyes may have influenced the decision-making process -- to say "I don't like this road" or notice that cell service had dropped out.

Another thought: I wonder if driving this road in daylight might have provided more cues to set off "the little voice in the back of your head that tells you something isn't quite right." The condition and maintenance of the road, the increasingly rough terrain, the lack of other vehicle tracks, the fact that (IIRC) they were gaining a lot of elevation -- these things are much less obvious when you're in unfamiliar territory and all you see is what's in your headlights.