On and on we go!
1) If he saw the Chinook the Chinook could probably see him and thus in sight of the surface. Thus ZERO evidence of being IMC at waypoint change? ANYONE DISAGREE?
2) I'm sure the '150kts' has been done to exhaustion, has it not? Do I not recall IAS 140kts and 10 kts tailwind? I would suggest HIS assessment of speed would be very unreliable.
Let's focus on the findings and not supposition/guesswork/imagination/paranoia.
Just in case, let's also drop duty times since the accident was early in the duty cycle.