The fill-in radio role was called off after Impey, who ran the broadcast company for 10 years, showed his hand with TPG and the takeover.
"Brent felt that with his relationship with TPG it was no longer appropriate, and we agree with him," said MediaWorks spokeswoman Rachel Lorimer.
MediaWorks understood his appointment to the TPG consultancy was only recent, she said, and it was not relevant to other times he had filled in on-air since quitting as chief executive.
Previous decisions to hire Impey to fill in for Michael Laws and Maggie Barry were unorthodox. Impey left MediaWorks with a significant payout and amid tensions with Ironbridge.
MediaWorks always maintained a warm relationship with the former CEO but those friendly relations did not extend to allowing a consultant for a company involved in a hostile takeover hosting a RadioLive show.
Given his expertise in broadcasting and media - he is a media lawyer - Impey is an obvious choice for TPG.
He is likely to stay on in a board role if TPG is successful in ousting Ironbridge.
Impey has a reputation as someone who speaks his mind and does not suffer fools gladly. Supporters say he fought for programming and retention of a strong news service.
MediaWorks has been under pressure because of a high debt loading that harks back to Ironbridge overpaying for the company in a highly leveraged buyout. Ironbridge has pumped in extra cash and restructured but still faces high interest bills.
The private equity company is assessing ways that it can keep its bankers onside and avoid taking a big hit on its investment.
Ironbridge has confirmed an Australian Financial Review report saying it is offering more than $50 million of new equity and to extend debt to 2015.
The issue for MediaWorks is whether its bankers hang in with Ironbridge in the expectation debt loadings and interest payments will go down and it can return to net profit.
TPG, meanwhile, is working to undermine Ironbridge by offering to buy the debt now at a discounted rate.
Apart from a period as a RadioWorks DJ, Impey's main role has been as a director of Yellow Pages Group.