It is possible that QF had this person (and I also have no idea as to his identity) lined up for this position for some time, and intentionally kept him out of the QF pilots' ranks to avoid future possible problems.
That he was able to stay current on the A320, through employment with the Government aviation branch headed by "The Minister for QANTAS", speaks volumes for those who have suggested where J.A.'s future salary might come from, once he bails out of politics!
We are all well enough aware that the choice of the A320 was not merely co-incidental with the fact that it is NOT a type currently operated by QANTAS (as was the B767 with Australian), and that, as such, AIPA would have little likelihood of success in laying claim to the crewing of it by the QF pilots.
Jet Star is, imo, just another example of another company's willingness to spend hundreds of millions of dollars to start another new company employing workers at lower than the established industry standard, because of QF's apparent failure to be able to successfully and amicably NEGOTIATE with their current employees' unions, and in the HOPE that there will eventually be a flow-on into the parent company.
It is a "tactic" that appears to be becoming SOPS for management worldwide.