Rex will get the Contract. Anyone else who considers bidding would suspect that Rex has enough tentacles within CASA to ensure that anyone who crosses it might get "The Treatment" from CASA like Dominic James did.
It does not require that the Board of Rex, with their deep political and regulatory connections actually do anything illegal, the mere suspicion that they have the ability to pull strings is generally enough to stop others from competing with them.
That is the way the possibility of official corruption works on markets; "bad money drives out good".
In my opinion the Rex political donations coupled with the bizarre behaviour of CASA and ATSB over the Pel-Air accident could perhaps cause a reasonable man to query CASA and the ATSB independence in this matter.