I saw the photos and it doesn't look like controlled descent without power. It looks like loss of control and high speed collision with terrain. I think this kind of VFR into IMC (especially at night) accident is just going to keep happening. It's a human error that is pretty hard to fix.
Maybe this poor guy went to a crappy FTU and was never taught about the dangers of VFR into IMC. Maybe he went to a good FTU and was that guy playing around on his phone during the part when the instructor was teaching PDM. Maybe he was taught the dangers but thought the instructor was overcautious and he was better and could "handle it just fine". Maybe the investigation will find out. Best of luck with that.
I seem to think that in commercial operations you need an instrument rating to fly VFR at night with passengers on board.
Please don't fly VFR over unlit terrain at night in lousy weather. Get an instrument rating. Fly IFR.