What about the conspiracy theory option?
Australian government is intent on increasing the capability of all arms of the ADF. Instead of trying to sell the voting public on increasing the size of the fighter fleet in the absence of a stated threat, they introduce an 'interim capability', in the form of an additional SQN worth of Super Hornets. If they can find lateral recruits, they can not only introduce the JSF without a capability 'dip' but also, through the back-door, increase the size of the fighter group by continuing to operate the SH through the transition and then replace the SH frames with an add-on buy of JSF at the end of the program.
