On the final day of submissions, Brisbane Supreme Court Justice Peter Flanagan also took issue with what Jones said in the witness box.

The high-profile broadcaster, journalist Nick Cater, Harbour Radio and 4BC are being sued for $4.8 million by the Wagner brothers, who claim they were accused of 12 deaths in the 2011 Grantham floods when one of the walls of the Lockyer Valley quarry they owned collapsed.

John, Denis, Neill and Joe Wagner also allege they were accused of a high-level cover-up with politicians, as well as corruption and intimidation, relating to their Wellcamp Airport.

Jones' lawyer Robert Anderson QC admitted on Thursday some of his claims about the prominent Queensland family could not be defended.

"We accept there must be awarded damages because ... there are some meanings that are not able to be defended," Mr Anderson said during closing submissions on Thursday.

But he argued the accused parties should not face a similar payout to the record $4.5 million originally awarded to defamed actress Rebel Wilson.

Mr Anderson said a similar payout to Wilson's original, reduced by $3.9 million on appeal on Thursday, was unjustified because Jones did not have the reach of Bauer Media.

Bauer, he argued, had a readership of 1.5 million and their claims portraying the Australian movie star as dishonest were proliferated worldwide, while Jones' audience was far less significant.

The court heard in opening statements in late April that Jones intended to rely on honest opinion as a defence.

But Mr Anderson said on Friday he will not be asking Justice Flanagan to make rulings on honest opinion after the judge warned a day earlier the defence would fail if his allegedly defamatory statements were found to be substantially untrue.

Jones and Cater gave evidence last month, with Justice Flanagan critical of the reassertion of their claims about the Wagners' alleged responsibility, given it was not based on the opinion of expert witnesses.

"They relied on what they believed at the time of publication," he said during closing submissions on Thursday," Justice Flanagan said.

"They repeated what has always been their beliefs, that the photographs, videos, eyewitness statements and accounts are sufficient to establishing a complex area of hydrology by causal link between the collapse of the bund at the quarry and the resulting deaths of 12 people.

"I haven't encountered that before."

A $2.5 million inquiry by then solicitor-general Walter Sofronoff in 2015 cleared the Wagners, with Cater last year settling with the family in a previous defamation action.

"Mr Cater ... says, 'I do not accept that (Sofronoff finding). I remain of the opinion that the bund collapsing at the quarry caused a catastrophic surge that resulted in the deaths of 12 people'," Justice Flanagan said.

"Therefore, any vindication of the plaintiff's reputation by a settlement in which he participated is very much lessened at least, isn't it, if not entirely dissipated?"

The hearing has concluded, with judgment expected in September.

Australian Associated Press