Looking at the over all picture I think CASA probably had to act, based on what has been reported (so far not disputed by Tiger) CASA had been investigating concerns since March, have issued a show cause notice. Then the ATSB starts an
investigation of a Tiger flight busting Lowest Safe Altitude on 7 June, and another flight descends below LSALT on 30 June (another ATSB
investigation), this was probably a last straw event.
There is clearly cause for concern, as this looks like more than a run of bad luck.