Peter Costello's resignation as Nine Entertainment's chair is the latest example of how a high profile role, built over decades, can be undone in a moment of poor judgement.

The altercation at Canberra Airport last Thursday with Liam Mendes, a reporter for The Australian, was the last straw for the Nine Entertainment board which was already embroiled in a crisis over the handling of sexual harassment and inappropriate behaviour allegations levelled at former director of news Darren Wick, who has now exited the media company.

Like any chair, Mr Costello's role was to ensure high standards of corporate governance and risk management were maintained and enhanced, rather than stoking concerns that Nine's board and senior management had taken their eye off the ball and failed to implement measures to reset culture in the organisation.

Mr Costello has consistently rejected claims that he assaulted Liam Mendes at Canberra Airport and late last week scoffed at suggestions that he needed to resign after eight years as chair and almost 11 years as an independent director.

In a statement released on Sunday, Mr Costello listed the company's achievements during his 11-year tenure, which included launching a streaming service, Stan and acquiring the most prestigious mastheads of Fairfax media.

As a former politician and senior leader at a news organisation that makes bread and butter from stake-outs and walk-ins, he signed off his statement with this final request:

"Note to journalists: I will not be doing any interviews or commenting further on any issues this weekend so no need to maintain vigil outside my home."

Embarrassing brain fade

Shareholder activist and media critic Stephen Mayne told the ABC that, despite a successful reign as treasurer under John Howard and ensuring the Future Fund delivered strong returns for taxpayers, Mr Costello's behaviour at Canberra Airport was a serious lapse in otherwise good judgement, even if, as Mr Costello said, he did not make contact with the journalist.

"It's an ignominious way to end his public career," Mr Mayne said.

Looking back, he could still say he was a great treasurer, that he was a very successful chair of the Future Fund. But obviously this is a very embarrassing brain fade," he said. 

"He needed to view the vision, apologise immediately, ring the journalist and try and save face. But by trying to tough it out, it just looked ridiculous. And ultimately he had to go."

Dead man walking

Peter Costello's instinct would have been to ride the crisis about his leadership out and to rely on support from Nine's board and the company's top management.

But despite initial support from the board, he was a dead man walking once the Canberra Airport vision went viral and became prominent across Nine's broadcast and newspaper platforms.

There was on-air criticism from high profile radio personalities — including Ray Hadley, Ben Fordham and Tom Elliott — who questioned Mr Costello's judgement and leadership.

"Boss, you've had a shocker," declared breakfast shock jock Ben Fordham on Sydney's high-rating 2GB.

Ben Fordham, like other journalists, had unsuccessfully requested an interview with Mr Costello to clear the air and to give him an opportunity to explain or defend his actions.

Challenging role 

So with Mr Costello gone as chair, effective immediately, a potentially toxic baton has been passed to his replacement Catherine West who steps up from her role as a long serving deputy chair.

But Stephen Mayne says Ms West's appointment will be crucial in rebuilding culture at Nine and restoring trust with staff and shareholders.

"I think it is good that Nine has chosen to go for a female chair in Catherine West because clearly, there's a need for cultural change after the Darren Wick scandal," Mr Mayne said.

"I think the optics of a first ever female chair as opposed to a shoulder-charging male neatly sends a message about cultural change at Nine."

Catherine West has a rich background in media with a 25-year background, dominated by time at Sky in the UK, once a key part of Rupert Murdoch's News Corporation.

Ms West's appointment sends a strong message about the need for cultural change at Nine and restoring confidence to Nine staff and unsettled shareholders after what appears to have been an attempted cover-up of the alleged behaviour, which has exposed major concerns about governance and management.