OM will have to work on my satire and I totally agree that now is too late for the ATSB to investigate, it'd be a bit like shutting the gate after the horse has bolted! No this matter has got Fort Fumble's pony pooh smeared fingerprints all over it.
First the ATSB, for some inexplicable reason, decide it's not within its remit to investigate even though that decision would seem to suggest a breach of ICAO Annex 13, of which Oz is a signatory State.
Next the regulator tells the QPS to butt out and they were going to investigate instead. Then a couple of months down the track do a complete 180 and decide it is no longer in their interest to investigate...WTF??
Finally the QPS Forensic Crash Unit are left to pick up the pieces and contrary to the lies, obfuscation, legal to-and-froing, contention on who will foot the bill for raising the aircraft etc..etc manage to put together a very concise and uncorrupted 'Final Report'!
However the fact still remains that the prime source of physical evidence still sits on the ocean floor....
So OM you are probably right that it is past the PNR for the bureau to investigate...but don't be fooled there is more to this sordid, sorry tale than meets the "aye..to be sure,...to be sure!"