I'm going to take a guess and say that the visibility got so poor that they took the best spot that they could see.
In the terrain described....it never gets too bad to see and LAND.
As a dedicated Rud Scunner, I saw occasions I could not get up and over a fifty foot power line or had to hover for a minute and blow some of the fog away... and more than once I landed in the middle of no where and shut down waiting for an improvement in the Visibility.
I have been in very similar circumstances as this Crew....ferry flight over new ground....thus a stranger to the area and ran low on fuel....but ALWAYS landed with enough to get to the nearest location that had Jet Fuel.
Worse case scenario....you call for the Fuel Truck to come to you....after you park next to a roadway of some sort.
The key was to go slow as needed and always know where the next fuel point was and always use that as your "Bingo Fuel State" plus that VFR Reserve Fuel you are required to maintain.
Never making flying into the Reserve a habit can be life saving in the end.
If you land out with Reserve Fuel in the tank....you never run out and wind up in the Trees or worse.
The Accident Report will be interesting reading on this one.....and at this time there is not enough information to fairly assess the cause of the crash.