The Minister can issue directions as he likes, but both CASA and ASA are still obliged under their respective Acts to conduct risk management and safety assessments of all proposed changes. There is also a requirement to consult.
The current Australian airspace policy statement also (logically) requires future NAS changes to be subject to "cost-benefit and the single common risk management framework" and "involve close consultation with the aviation industry".
The AAPS can be changed to remove all that but the risk and safety assessment processes are still required, and in any case any attempt to implement a change that does not have demonstrable safety benefit, does not have any cost-benefit or without consultation isn't going to sit well, as we've witnessed in the past.