John Tyson, 50, lost his wife, Donna Rice, and son Jordan in the 2011 Queensland floods, which also left him homeless.
In December 2010 he was diagnosed with a kidney condition similar to the one that killed Jonah Lomu, leading to the forging of an unlikely trans-Tasman friendship with his widow Nadene Lomu.
Mr Tyson is anxious to help Lomu's family, and has suggested a charity boxing match to help Nadene and her sons.
"I can't do much but offer what I've got," he told Checkpoint with John Campbell. "I could either play rugby, play rugby league, or box.
"I could get a couple on the chin - there'd be plenty of people who'd pay to see that."
Mr Tyson was initially told that his illness gave him around a month to live, but now manages his kidney condition with high doses of a drug called Pragmazone, which he was told had a one-in-a-million chance of working.
Though Mr Tyson has suffered from relapses, he would not die from kidney failure or have to go on dialysis, he said.
Over 300,000 people in New Zealand and Australia signed a change.org petition to give Mr Tyson's son Jordan a posthumous bravery award, after he asked rescuers to save his younger brother Blake first: in the meantime, he and his mother Donna were swept away.
The petition is the largest ever of its sort on the Australian branch of the site; Mr Tyson will accept the medal on behalf of his son in May.
He wanted to thank each and every New Zealander who had signed the petition: "I hope that they recognise that a little bit of that medal belongs to each and every one of them.
"It is for the people."