Obvious Question: What is the basis for the provision of CA/GRO at any aerodrome outside an MBZ?
Assuming you mean legal basis, CASR 139.400, 139.405
So clearly the provision of CA/GRO services is not supported by CASA at this point in time.
Bush Lawyering 101?
There would be an Instrument or amendment somewhere declaring references to MBZ be CTAF-R in CASRs and other documents such as MOSs, somewhere around the time CTAF-Rs came in.