Interesting... so it appears that the registered operator is appointed by the owner (without any description of the form that must take?), and any cancellation/appointment takes effect as decided by the owner, not upon acceptance by CASA.
The owner is only required to notify CASA within 14 days of any change.
So then the question might be:
What responsibilities do the owner and registered operator respectively have, if the owner allows someone to operate the aircraft without the knowledge and approval of the registered operator?
Also, if the owner allows or asks someone else to perform the duties of the registered operator after the date the registered operator was changed, could that be considered another (defacto) change of registered operator? (A stretch perhaps, but I suspect there will be a few interesting arguments put before this is ended.)