I don't mean to second guess the TSB.I am sure they will eventually get to the bottom of this tragedy.
Also,I certainly don't want to call into question the experience and the skill of the two pilots.By all accounts,those skills were unimpeachable.I extend my deepest sympathies to those left behind.
However,I would just like to add that, if indeed it was a case of CFIT (just speculating at this point with very sketchy information ,so please,bear with me) then, we have to remember, that spatial disorientation is impartial and the great leveller.It can strike the very experienced and the inexperienced equally and unexpectedly.Secondly,if the pilot flying is disoriented, the pilot not flying may not realize what is happening quickly enough to take over and rectify the situation.SD rarely hits the pilot not flying.If they were accelerating and still a bit low, it all could have happened in a few seconds before the PNF could intervene.
Again, not disparaging the dead or making judgements.Just offering a point of view.
Alt3.