You also concede that the "....lead investigators, were unable to determine the cause". To their credit, they had the integrity not to deviate from the facts into fantasy.
I didn't concede a damn thing. I just assumed that everyone was smart enough to realize that the American NTSB doesn't suffer from the "Saving Face" virus!
US NTSB just call things the way they are. If someone looses some face or pride, so be it!