The options are endless really, explosion, structural failure, skylarking, suicide, severe bird strike or just being plain unlucky in some way or another.
I would suggest waiting another year until the ATSB sort it out before asking why.
So why don't you do as you suggest and leave it be, instead of throwing out options three and four there. I was lucky enough to have met Hadleigh a number of times, and I am fairly familiar with his aviation and personal background. I would be extraordinarily surprised if either of those were an explanation, and I think to even suggest it without one ounce of evidence is grossly insulting. Honestly, how crass...
Hadleigh, I hope to goodness that you are sitting on an island somewhere waiting to be rescued. Everyone down here does. God be with you mate.
TT