Lenore Taylor is a measured and respected journalist, and she has confirmed on twitter that:
the sources (multiple) have always stuck by what they told me - and subsequently told several other journalists.
Either Lenore Taylor's sources or the Prime Minister have told substantial untruths about what happened in Cabinet. It's not, and should never have been about Waleed. Half the internet was reposting that old article and belting Morrison about it. It was already sitting there on the public record and it raised, prima facie, legitimate and serious concerns.
The sources should put the national interest first and either retract, if they concede they may have misapprehended things and now agree with the PM, or speak up in full about the matter in Parliament. Because if they stand by their stories then the PM has lied and must leave public office.
If we had a mature political culture and party members on either side put the national interest first, rather than the party interest, this would be axiomatic.
The attacks on Waleed were just a diversion, another example of Trump's trademark contempt for criticism and the press being mainstreamed by the right, as it coyly sizes him up and likes much of what it sees. And they smack of desperation.
Except in the most egregious cases, any mention of defamation law should be beneath the office of the most powerful person in the land, who has access to parliamentary privilege, a large office of political hacks and an entire department of his own advisers.