Liverpool said:There are a few laws that mention the Head of State as being the Governor General....just saying.
from your wiki link:
The dispute over who is Australia's head of state centres around the question of whether the Australian monarch or the Governor-General of Australia is the country's head of state; the term Australian head of state, or any variation thereof, does not appear in either Australian or international law.
seems to me the only people who want to argue the queen is not the head of state are those that want her to remain head of state, but think their argument is stronger by denying it.