By my reading:
Life imprisonment. They removed the death penalty for that crime.
Under section 80.1 of the Criminal Code, a person commits treason if he or she:
causes the death or harm, resulting in death, imprisons or restrains the Sovereign, the heir apparent of the Sovereign, the consort of the Sovereign, the Governor-General or Prime Minister;
levies war, or does an act preparatory to levying war against the Commonwealth;
intentionally assists, by any means whatsoever, an enemy, at war with the Commonwealth;
intentionally assists, by 'eany means whatever', another country or organisation that is 'eengaged in armed hostilities' against the Australian Defence Force (ADF);
instigates a person who is not an Australian citizen to make an armed invasion of the Commonwealth or a Territory of the Commonwealth; or
forms an intention to do any of the above acts and manifests that intention by an overt act.