I think the reported damage to the MGB and subsequent repair at AB will be a big factor in the ongoing investigation. I assume that this avenue is being followed.
I posted previously of an engine failure in a single engine helicopter with the determination that the root cause was believed to be that an internal gear had been dropped during assembly causing damage to the gear leading to it's in flight failure. It was interesting day for me.
Much as many think they should be privy to all information I fear they will have to wait for the final report.