Seems a lot of these cfit (if that's what happened here) collisions, occur in met conditions that to the human senses are 'IMC', just that we have this inbuilt desire to continue to want/hope to see things outside the cockpit to remain VMC especially if we haven't planned to fly IFR. The purist can argue that 5 mile vis and 400' cloudbase are VMC, the counter argument would be that it was at night, over unlit terrain with no/few geographical features that could be seen, no horizon and without NVS so would need to be flown by reference almost entirely to instruments.
Did the aircraft have an autopilot and nav system at all?