Alan Jones' legal team has argued against a Rebel Wilson-like defamation payout after dropping his honest-opinion defence and admitting some claims he made about the Wagner family were indefensible.

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

Mary Wagner (centre), her son Denis Wagner (right) and members of the family leave the Supreme Court in Brisbane, Thursday. Credit:AAP/Dan Peled

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.