HGW, yes there was definitely human error involved but when the ACTU take legal action to ensure that adequate training is provided then even I sit up and take notice.
Carrying a suspect device or suspicious article into a crowded terminal area reeks of that lack of training mentioned.
Brutus, no need to seek Woomera's action as its been done by your request.
As for it being "security in confidence" I could find no reference, especially on the widely circulated reference cards, one of which I found in an aerobridge after it had been walked over by god knows how many punters !!!
This priciple is widely used worldwide by a number of airlines.