Gaunty
You are confusing the possible outcomes with the possible explanations for inaction by ATSB.
The 'exact opposite' to the outcome in the passage you quoted is envisaged in my list of 3 possible outcomes above. (See outcome 2).
The only reasonable explanation I can see for inaction by ATSB ain't that outcome.
Any refusal by any aviation accident investigatory body to retrieve OBR equipment is always going to look absurd.
If the equipment were in the Mariana Trench and there were no controversy surrounding the incident, there'd be a reasonable excuse.