Call me names if you like, but I wonder if the lack of any visibility of the NGA co pilot in all this is somehow connected with the ATSB's refusal to retrieve the CVR.
My sporting dive limit is 42 metres, but the professionals go way deeper.
I suspect that there is something very embarrassing to the ATSB, CASA and perhaps other powers that is on that CVR.
I'm bringing this up because I have seen a lot of treachery and very strange things in my business career. I learned the hard way that truth is stranger than fiction, and I suspect that what is on that CVR might reinforce that belief.