Assuming that they have the CVR tape, that would preclude any official investigation and piss off anyone who might be inclined to help if they managed to scramble through official channels.
Further, the CVR tape might not be spectacularly useful for a controlled flight into terrain accident in instrument conditions. There is a fair chance that the first problem the cockpit crew encountered was the impact.
On the other hand, it might show navigation equipment failures-say those VOR transmitters-and traffic control communication problems.
