Why don't they just put an Administrator in for 90 days ( chapter 11 ) and return aircraft they don't want, lay off the staff not needed, change the management, standardise the fleet (777/737/A330), piss Jetstar off emerge from administration chapter 11 and plough on ???
Because we don't have Chapter 11, and because an administration would mean the management would lose all control, and they might even be found to have broken the law. Not saying they have, just saying when an administrator takes over, it's down to the administrator and the courts what happens. Unless they became insolvent, it's not going to happen.
The US Bankruptcy code is very different to Australian law.