The Federal Government proposes to amend the Crimes Act 1914 so as to be able to jail any body of persons, incorporated or unincorporated, which by its constitution or propaganda or otherwise, advocates or encourages the doing of any act having or purporting to have as an object the carrying out of a seditious intention.
Seditious intention means an intention to bring the sovereign into hatred or contempt; or to urge disaffection against the constitution; the government of the Commonwealth; either house of the Parliament; to urge another person to attempt, otherwise than by lawful means, to procure a change to any matter established by law in the Commonwealth; and to promote feelings of ill-will or hostility between different groups so as to threaten the peace, order and good government of the Commonwealth.
Here's a problem with law: it's not definite, it's not specific. It's left open in order to give judges some wiggle room when applying the laws - I think the legal term is "allowing interpretation". This is why two people committing the same crime may get completely different sentences - community service versus jail time, for example.
By the cited definition of "sedition", expressing discontent with the government and encouraging people to vote against them could be deemed seditious and with that you could be placed in jail or under house arrest. Under new laws if anyone else figures out that you've been placed under house arrest and mentions it to someone in the tea room at work, they could be jailed for seven years.
So, basically, if the current government feels like it, they can jail Labour, Green and Democrat voters; since they advocate voting against the government. People are often quite strident in their opinions on the matter and could very easily be described as expressing hatred for Johnny "Lying Bastard" Howard and his minions. It's seditious to express a strong opinion that the government are a pack of arseholes who doing horriffic things to our way of life.
An extreme interpretation? Not really. Punching someone several times in the face is "assault". So is putting a hand on their shoulder. That's legal interpretation.