Then he just needs to appoint himself as Chief Justice of the Supreme Court and become the President of the Senate to fulfill his dream of running the entire government.
Our former prime minister actually did something like this. He secretly appointed himself as health minister, finance minister, industry minister, home affairs minister and treasurer. It was quite a big scandal that only came out after the election that kicked out his government and threw a lot of ministerial decisions made during that time into legal doubt, though nothing ended up coming from it.
Morrison was a lazy shit and only used his secret ministerial powers a few times, he just wanted to have the power for himself. His stated reason was "in case the existing ministers became incapacitated by COVID", but we already have assistant ministers that could fill in if that happened.
I never saw any arguments against the Voice that weren't either simplistic ideology ("it's racist to have an advisory body for indigenous people!") or outright lies and conspiracy theories. Claiming that it wouldn't have gone far enough isn't a good argument to do nothing instead. Does anyone really think that a treaty is more likely now than if we had voted yes?