Wow, what a thread and all because a pollie was on board!
I agree with AusATCO, 4711 and amos 2. It's the final "Safety Net" and possible lack of the "big picture" scenario from the flight deck - talking generally here - and of course, QANTAS SOPs.
The REAL problem in this case is that someone on the flight deck (allegedly) told the SLF (PAX) that the reason for the go around was that, "there was another aircraft on the runway". Wow! Where do we go from here? Did the crew LIE to the PAX?? What ELSE do you say in this circumstance? Trying to explain the complexities of aviation to your average punter is really a waste of time......unless there is a ferkin, big-mouthed pollie on board!!