Noriega was held as prisoner of War. I don't think the US is planning a coup of Australia beyond lopsided trade agreements. Besides, Noriega was just a disobedient puppet like Hussein.

He was originally detained as a prisoner of war. He was then flown to Miami where he was tried and convicted on drug trafficking and money laundering charges in a civilian court. Diplomatic immunity certainly didn't help him, and I doubt it would help Assange either.