The regulations in force at the time required the recovery of the recorders if possible. For some reason the ATSB sought to play with words and rely on an interpretation of regulations not in force at the time. This was a key reason the Senate committee was dissatisfied with Dolan's evidence ay the inquiry.
At this point the best thing would be for the ATSB to ask an independent body to recover the recorders. Either the RAN or a Police agency. That way we could at least be confident if they were there or had been removed.
If they are present an independent agency (? Canadian TSB) should attempt to recover the data. If there is no data able to be recovered, we need to be confident that this really is the case.
If they are gone there needs to be an investigation into the circumstances of the disappearance.