CASA have had the power all along they just haven't exercised that power. I think you will find that there is pressure coming from all corners for CASA to do something about the QF situation.
Also remember that if QF spear one in and the regulator was found not doing it's job diligently, (not that hard to do really) then CASA can be sued. If you start looking at damages for 400 people then its start getting expensive and some serious investigations will be held into the government. Something that the government and CASA don't want to see.