I do like these comments on the ADF Serials board
"The US government has already allocated F-111s to community museums in the United States."
"Work that needs to be done to demilitarise the aircraft is defined in a “U.S. Government Demilitarisation Manual” which is freely available online. Currently the Defence Materiel Organisation is actively discouraging potential tenderers from referring to this manual because “reference to the Demilitarisation Manual on its own can be confusing and misleading.” The only thing confusing about the Demilitarisation Manual is that its requirements are significantly less stringent than those imposed by the Australian government!"
"This deterrent factor is now working against the aircraft in that it is deemed to be an ongoing threat. The well-equipped RAAF stopped using the F-111 because the aeroplane was proving difficult to keep in the air. How could a non-nuclear configured, demilitarised airframe, out of the maintenance schedule, and minus engines, pose the slightest threat to anyone, particularly when no other nation on earth operates F-111s?"
Sounds to me like the Aust Gov't just didn't want to go through the hassle.