Former defence minister Christopher Pyne has declared himself on the register of lobbyists, with one of his company's clients a defence training and consulting firm.
But outgoing secretary of Prime Minister and Cabinet Martin Parkinson said that wasn't relevant to his investigation of whether Mr Pyne's consulting job at EY breached ministerial standards.
GC Advisory, a consulting firm owned by Mr Pyne and his former chief of staff Adam Howard, was registered in September 2018, and Mr Pyne was included as a lobbyist on July 29, 2019.
Mr Pyne also took on a part time role advising consultants EY on expanding their Defence work in June, after the job offer was made while he was still a minister.
Labor senator Jenny McAllister and Dr Parkinson went head to head on whether this information showed Mr Pyne was breaching ministerial standards.
According to the ministerial standards, former ministers shouldn't lobby or advocate with ministers, parliamentarians, public servants or defence force members on issues they were responsible for as ministers within 18 months of leaving office.
Dr Parkinson was asked to investigate the new job and previously found Mr Pyne, and former foreign minister Julie Bishop, who has taken on a non executive director role at international development firm Palladium, had not breached the standards.
In the hearing on Friday morning Dr Parkinson again drew attention to the difference between experience as a parliamentarian and specific knowledge gained as a minister.
Clients of CG Advisory include the duMonde Group, which has been contracted to provide services to the government. Mr Pyne was added to GC Advisory's register after Dr Parkinson's inquiry had finished.
Dr Parkinson drew a distinction between registering as a lobbyist and actually lobbying, comparing it to Mr Pyne having ambitions to play AFL football but may never get a game.
Dr Parkinson said he didn't speak to either EY or Palladium to verify conversations he had with Mr Pyne or Ms Bishop, because he assumed he had not been misled by either former minister.
Dr Parkinson said he was working with the assumption of innocence, not the assumption of guilt.
"Perhaps I'm naive Senator, but when ministers or senators of MPs tell me they are going to do something I tend to take that at face value," he said.