As I've repeatedly said, either Prime Minister and Cabinet Department folk do over CASA or wait for three smoking holes and a Royal Commission to do it the hard way.
My guess is that the easiest way for PM & C to nobble CASA would be to outsource their legal services and put an intermediary in there who has to be satisfied that the legal/regulatory action meets the model litigant requirements as well as being cost effective, necessary, procedural fairness, natural justice, etc., etc., etc.
If I can find the time in the next few months I might try and find out who knows who is doing what in the public service these days, but I expect Heffernan and Co. already know.
I still fondly remember Robin Hocking (RIP) whose scholarly economic work triggered the debate over and the eventual ending of the Two airline policy.