And on top of all of those good reasons why it is very unlikely to happen, in order for a zoo in Australia to receive wildlife export permits, the recipient institution must be "approved" by DEH, and be part of a managed program fopr the species. If animals are to be exported for release to the wild, we would have to be part of the release program in the range state, and prove that the animals are required by the range state as part of a coordinated release program. I could be wong, but to my knowledge, this isn't the case with cotton-tops.
It sounds all nice and conservation-minded to suggest that we pop these guys into a box and set them free in the wild, but in reality, it's far, far, far from a simple process logistically, and these animals are not really suitable candidates for release. One of them is 26 years old for a start!