The former Labor prime minister issued the spray during a discussion at La Trobe University on Wednesday night and in reference to the defeat of the 1999 referendum.
Mr Keating said he'd been approached by the republican movement to help reinvigorate its campaign following the death of the Queen but wasn't interested in advocating for the cause.
"If Australians have so little pride in themselves, so little pride that they are happy to be represented by the monarch of Great Britain, why would somebody like me want to shift their miserable view of themselves," he said.
Mr Keating said he believed the royal family would have been "so glad for the referendum to have passed" and for Australia to break away.
He also took aim at the Quad security dialogue between the US, Japan, India and Australia, saying it was not intelligent to be "owned" by the US.
"The Quad is a piece of strategic nonsense," he said.
Mr Keating also said the government should abandon the AUKUS partnership, which will deliver nuclear-powered submarines.
He said Australia should not get involved if tensions over Taiwan boiled over into conflict and the US would lose to China.
"Taiwan is not a vital Australian interest," Mr Keating said.
"We should be no more interested in the political system of Taiwan that the political system of Vietnam or Kazakhstan."
"The chances of the Americans having a victory over Taiwan is nil in my opinion and why would we want to be part of that defeat?"
Mr Keating said "we live in a Chinese world" and Australia would be left high and dry in the region, with the US able to walk away following a defeat.
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