1. What is David Cox' work background ?
2. Did he make the comment about "one engine" ?

Best advice anyone can give Mr D Cox is that is better to remain silent and be thought of a fool, than to open your mouth and remove all doubt.

As a passenger on QF26 from LAX, I can report it was more than a precautionary shutdown due to vibration.
During climb there was a huge bang, along with a bit of a yaw, then climb continued seemingly normally. Of course being told to remain calm always makes people less than calm.
Soon we heard from the flight deck that they had shut number one engine down.
After dumping of fuel, we returned to LAX to a perfect greaser of a landing, compliments to the crew.
As I was in a left side window seat I could see the maintenance crew checking out number one engine, and after a while sitting on the aircraft we were told of a turbine blade failure.
I imagine the sparks seen by some would have been most impressive!

Always nervous of loud bangs, at the time wondering whether all was contained, or not.

Doubt it! A lot would have flown out the back.