Never mind the excellent analysis of the facts on the ground, what we are talking here is CORPORATE CULTURE.
I am sure that Jetstar has miles of glossy manuals regarding the procedures and systems that guarantee (on paper) that its operations are worlds best practice regarding safety.
However if the corporate culture is to selectively apply and interpret those procedures for its own profit, then they are worse than useless.
That leaves the Crew in the classic "Double Bind" dilemma. - a formal legal requirement to apply company fatigue procedures and standards to their operations - but an informal management practice (or even threatened practice) of penalising or discriminating against anyone who avails themselves of the personal protections of the formal system
I had this one tried on me by Exxon as a young engineer in charge of Twenty one million litres of petrol and avtur - with Two feet thick of manuals that I was supposed to follow, but without sufficient money or staff to allow me to comply. Complaint simply resulted in a query about whether I was a "company man" and did I want to keep working here? The choice was obvious, shut up and remain personally exposed until my next promotion or leave. I left after that. The Longford gas plant explosion subsequently showed Exxon's procedure at its finest - the blamed the dead for "not following company procedures" and it took a royal commission to sheet home the blame to Exxon and exonerate its overworked and undertrained victims.
I don't expect CASA to hold Jetstar to account. It would take balls of steel, and exceptionally ironclad committment to safety, from the top of CASA all the way down to effectively face off Jetstar, stand up to them and say "Yes, I know what your procedures SAY Mother*&*er, but I can tell that this is what your managers are really doing!". There are no public servants in Australia anymore who could or would do that.
What will happen is highly predictable. There will be a fatigue or maintenance related accident and Jetstar will blame the pilots for "not following company procedures" even though those procedures are now honoured in the breach.