Nowhere in Australia is currently under a large or long lockdown. A few small communities are under short ones.
Isolation of sick people and those testing positive is understandable. Isolating healthy people, those who test negative, and those who have already had the disease and developed antibodies is blatant tyranny.
I don't believe that requiring people who have been exposed to a disease during the incubation period of that disease violates is tyranny. I would add those to the first two groups you mention. Testing negative at the start or in the middle of an incubation period is no sort of guarantee that a person is safe.
I would generally agree with you that quarantining those who have already developed antibodies as a result of infection is unjustified. But that isn't the case in the situation we're discussing and as only 300 people in the Northern Territory have had COVID, I doubt it's relevant in any of the cases there.
You are in agreement with those who chip away at liberty a little at a time, justifying usurpations in the name of safety and security, which never ends well for the people.
Freedom is a zero sum game. The people of Australia lost the game when they gave up their natural right to bear arms.
Communists (tyrants generally) who control governments are never satisfied with the power they have. History has shown that they will use any means necessary to increase that power until they have it all. Today they have a powerful weapon at their disposal, the virus; tomorrow it will be something more innovative and divisive, like Climate Change.
No government-declared emergency, NOTHING, supercedes an individual’s God-given rights.
I forgot to mention: the most sacred weapon of the tyrant is division. Divide and govern is their Maxim.