I was too young back then to have followed it, & I don't remember this story.

However, I would condemn the SIngaporeans for doing it as well.

Taking a human life in the name of law is never acceptable, in my (very popular) opinion.

However, it doesn't sound like there was "no outrage whatsoever":

A plea for clemency by the Australian Government was rejected in October 2005. Members of the federal and state parliaments appealed for the decision to be reconsidered and clemency to be granted.

On 21 November 2005, the Australian Government was considering a request made by Nguyen Tuong Van's lawyers to apply for a hearing at the International Court of Justice which required the Singaporean government's agreement to its jurisdiction. However, Foreign Minister Downer considered it unlikely that the Singaporean government would agree. On 24 November 2005, Victorian Attorney General Rob Hulls met with Singapore's Senior Minister of State for Law and Home Affairs Ho Peng Kee to press the case for clemency but was unsuccessful. On 28 November 2005 Australia's Human Rights Commissioner, Sev Ozdowski, said Australia must keep pressuring Singapore to abandon the death penalty, even if it proves too late for Nguyen.

After his sentencing in March 2004, anti-death-penalty campaigners were reported to be inundated with emails from Australians offering support for Van Tuong Nguyen. Politicians and religious figures made pleas for clemency, but these were rejected by the Singaporean government.

One day before Nguyen was hanged, a lawyer launched a last-ditch legal tactic, charging Nguyen with drug related offences in the Melbourne Magistrates' Court, which he hoped would allow the Australian Federal Government to extradite Nguyen. However, Justice Minister Chris Ellison ruled out extradition, saying that the Commonwealth Director of Public Prosecutions would not have attempted to prosecute Nguyen in Australia.