Because in a court case claims must be proven - so a solicitor can utilise a more passive strategy, relying on the weakness of the accusation's proof to not meet the required standard.
In a tribunal case, claims are decided only on the balance of probabilities - so the defence strategy must be much more proactive in using the evidence to show you didn't do anything wrong, rather than relying on the opposition's evidence "failing to prove" anything.
This tribunal case appears to have had a poorly prepared defence. The angle of bank picture from a few posts ago would have been an obvious thing to bring to the court - along with flight manuals demonstrating there is no angle of bank limit, and so on.
Having said that - CASA is "dammed if you do, dammed if you don't". This very thread is saying "Why no action on THIS video", yet when they do take action it's "Why attack THIS bloke!" (Note - I think that this heli pilot is innocent of any wrong doing, on the basis of the video and pics I have seen.)