Either CASA or AirServices can approve the flight.
Here's the relevant section from CAO 20.18 below, bolding is mine:
Originally Posted by CAO 20.18
9B.8 On and after 12 December 2013, any aircraft that is operated at or above FL 290 must carry serviceable ADS-B transmitting equipment that complies with an approved equipment configuration by meeting the conditions for approval set out in Appendix XI.
[...]
9B.12 Paragraphs 9B.8 to 9B.11 do not apply to an aircraft if:
(a) the aircraft owner, operator or pilot has written authorisation from CASA, based on a safety case, for the operation of the aircraft without the ADS-B transmitting equipment; or
(b) the equipment is unserviceable for a flight, and each of the following applies:
(i) the flight takes place within 3 days of the discovery of the unserviceability;
(ii) at least 1 of the following applies for the flight:
(A) flight with unserviceable equipment has been approved by CASA, in writing, subject to such conditions as CASA specifies;
(B) the unserviceability is a permissible unserviceability set out in the minimum equipment list for the aircraft and any applicable conditions under subregulation 37 (2) of the Civil Aviation Regulations 1988 have been complied with;
(iii) ATC clears the flight before it commences despite the unserviceability.
EDIT: Actually, disregard. This is a CASA problem. Undecipherable regs...
