It's funny that so many people posting here are buying the line given in the media.This is the same media that the same people openly have a go at.
Of course the airline would try and blame someone else.I have been on umpteen delays because of technical or weather glitches where the passengers were not allowed to disembark.The last thing the airline or airport wants is for the passengers to disembark.It does not matter if the aircraft is flying to the US or the UK.It (disembarkation) causes problems and if you have them all in the same place that is your preferred option.
The problem lies with the nature of the beast and that is when will the problem be fixed.It's like 'how long is a piece of string ?'
How do you know when it will be fixed when the engineers don't and if it goes beyond the crew hours limitations then you take them off which is exactly what happened.That has not stopped so many experts here quick to have a shot at US.
The big problem with most people is that they can't see the forest for the trees.
The problem is/was that the aircraft (QF's not the US governments) had a technical problem preventing departure.
End of story.