The ABC has dropped an investigation into allegations of political interference at the broadcaster, because ex-managing director Michelle Guthrie doesn't want to be part of it.

Acting chair of the ABC Dr Kristin Ferguson has revealed the organisation's probe has fallen through, at a Senate inquiry into the potential interference.

The allegations emerged after the ABC's board sacked Ms Guthrie halfway through her five-year term in September.

In an 11-page dossier handed to board directors a few days before she was shown the door, Ms Guthrie claimed then-chair Justin Milne had encouraged her to fire journalists, after senior government figures had taken issue with them.

Mr Milne denied the claims, but resigned as chair three days after Ms Guthrie's departure, after excerpts of the dossier were made public.

The ABC board decided to investigate the issue on the same day it decided to fire Ms Guthrie on September 23.

But Ms Guthrie told the ABC in January, while in the midst of taking legal action against the organisation, that she would not be part of the investigation.

"Ms Guthrie advised us that in light of the federal court proceedings, she was not willing to participate, and the board resolved ... that we would not be able to progress that investigation," Dr Ferguson said on Tuesday.

Ms Guthrie and the ABC reached a confidential resolution on her court action last Friday, with the broadcaster unable to reveal what settlement payment it may have involved.

The sacked boss already received $911,000 upon her termination.

It was also uncovered at Tuesday's hearing that Mr Milne had told staff at radio station Triple J that activists who get ahead of public sentiment can be "burnt at the stake", as they discussed moving their Hottest 100 countdown from Australia Day.

Triple J content director said he expressed the sentiment at a meeting in October 2017, also attended by Ms Guthrie and two other ABC staff members.

The meeting came after a year-long review into changing the date of the countdown which found most Triple J listeners were happy to have the date moved, and recommended the change occur.

"He said it's our job to look after the interests of the whole ABC," Mr Wards told the inquiry by teleconference.

"Justin was talking about a book that he was reading to do with social change, and in that book it described about how activists who get out in front of public mood can end up - the words he used were 'getting burnt at the stake' - and that we wouldn't want to be burnt at the stake."

Mr Milne also told the ABC staff, who pressed their case, that former prime minister Malcolm Turnbull wouldn't be pleased by the change.

"He said: 'Malcolm will call me and tell me I'm crazy'."

After the meeting, Triple J decided to keep pushing for the plan, which was later approved by the board.