Australia has,
collectively, determined capital punishment is a barbaric, vindictive and irreversible custom, inappropriate in our society.
And if you don't think mistakes are made, read about
Timothy Evans.
The Australian Government is totally correct in seeking a common protocol in dealing with terrorism (or any other crime) on bilateral air services between Australia and the US (and any other country).
One could also have some concerns that gun toting dudes from a gun happy society may find it appropriate to intervene in minor in flight disruptions - inebriated or disruptive passengers etc - to the detriment of other passengers when lead starts flying around in an aluminium cylinder, and the crew are powerless (due to law and locked doors) to intervene.
Voice, your statistics aren't quite correct.... A few years ago two Aussies came home in boxes from an Asian country after being hung for a drug related crime which would probably have earned a relatively minor custodial sentence in Australia.
And before I get dumped on from a great height ....... I am as vehemently opposed to crimes involving aircraft, drugs etc., as any other Australian. Maybe more so.......