No, this is not true. The Australia Government cannot intervene in any penalty imposed in a foreign country on an Australian national. In fact there are about 3 Australians facing a firing squad in Bali and there was an Australia who was executed in Singapore back in 2005. The Australian Government can make an "appeal" but that's about it.
All appeals for clemency were rejected. Singapore's High Commissioner in Australia, Joseph Koh, said Singapore carefully considered appeals from Australia but decided the law must be applied consistently. "It had to treat Nguyen consistently with similar past cases, and apply the law equally to Singaporeans and foreigners," Mr Koh said.
http://en.wikinews.org/wiki/Australian_Van_Nguyen_executed_in_Singapore
Should AB ever be tried and convicted of the cover up and/or murder of his daughter Zahra, I personally don't believe he will be eligible for the International Transfer of Prisoners Scheme, my opinion is based on nothing more than past experience. I have never, ever heard of one case like that happening.