Not correct.
Section 9A is not the source of any power. Section 9A is a requirement imposed on the exercise of CASA’s powers and the performance of CASA’s functions - whatever they happen to be from time to time.
To the extent, if any, to which CASA has powers or functions that relate to the designation of airspace etc, the considerations will apply to the exercise of those powers and the performance of those functions. Those powers and functions wax and wane as the interminable ping pong match of airspace-related responsibility allocation continues.