A quick read of the decision shows us the problem. The learned judges have taken note of the purpose of the act - to prevent accidents. One way to do this, consistent with the act, is to prevent aviation entirely. There is no modifying clause such as "consistent with reasonable commercial endeavors" or suchlike.
So the judges at about sect 51 have simply said that the law requires interpretation with regard to the purpose of the act, and if CASA interprets capers operation as RPT then that trumps the grammatical interpretation used by the tribunal.
To put it another way, words mean what CASA say they mean, not what you think they mean.