I don't think it was ever claimed to be an event!
Different internet sites use different altitude sources.
Flight Aware and Flight Radar shows the overflight of the harbour at 1200'.
Air Services webtrak shows it at 1700'.
Qantas media have just released a youtube video of the flypast. The altitude in relation to Centrepoint Tower gives a good perspective!
A pity the video didn't include the orbit!