The Orions from the old Aero Union fleet are now being operated by Airstrike and possibly one by Buffalo. The FAA approved design exists and has for a number of years. Their grounding had nothing to do with their lack of airworthiness,Purely business deal. Note that Canada's Airspray, Buffalo and Conair have operated the L!88 as air tankers for number of years. All up about 16-20 L188s and Orions are current so the aircraft must have a few supporters?
However looking at the current conversions most of those operators are heading towards Bae 146 types.and away from Electras.
If the Federal govt decided to go that way it has nothing to do with the RAAF as they will be disposed off via Defense Supply and probably converted in the Airstrike facility in the US?.
Wunwing