What a very unfortunate accident. I was privileged to know Herb Thwaites when he was a Flight Test Officer with DCA (or it might have been DOT) in the 1970's at Parafield. He talked a bit about his RAAF flying and I didn't ever notice that he had lost a leg. I recall that he flew the USAF B47 for some reason, I think at Woomera. He also flew Meteors and Mustangs. He was just a nice guy doing a serious and responsible job, testing civilian Private and Commercial pilots for licence issue when I knew him. I certainly did not know anything about this accident.
For what it's worth just think about the affect it must have had on Herb. Obviously the person who has successfully forced this inquiry was also very much affected as were many others who were directly and indirectly involved.
Reading the full report, it is obvious that Herb was trying to indicate the location of the shark to the surf boat. That last turn was very steep and slow and the Wirraway flicked from a left bank to a right roll and hit the beach and killed people. It was certainly not a suitable aircraft for Shark Spotting operations. A Tiger Moth or an Auster would have been better.