Very strange
Yandle's eyewitness account, and his alleged qualifications as an amateur astronomer, give this report some substance.
It was visible for too long to be an object in earth orbit, and since it's motion to the NE is not with the rotation of the celestial sphere, it suggests the explosion was from a moving object fairly near earth, but not in orbit around it. I would expect an amateur astronomer would have noted this, but it's not likely the press would have quoted him accurately.
Another possibility is a suborbital explosion at extremely high altitudes. Isn't there a missile test facility in the outback, somewhere? Is Woomera still active? More information on this sighting is eagerly anticipated.