"Kevin's a legend on Tyneside and I think anybody looking to buy that football club would not be very smart if they didn't have Kevin involved in some capacity, that's if Kevin wants to come back," added Nathaniel.
"If I was advising anyone that was buying the club I would certainly suggest Kevin would be the right man for the job."
Keegan left his second spell as manager on Tyneside on 4 September, only eight months after returning to St James' Park.
His relationship with Ashley deteriorated rapidly and his exit caused fury among Magpies' fans, who demanded the owner sell the club.
Toon takeover serious - Nathaniel
Ashley has since put Newcastle up for sale, saying he is unable to watch the team due to fears over his family's safety.
Nathaniel, one of whose parents is Nigerian, runs football and entertainment consultancy NVA Management and he is the frontman for the bid.
The four entrepreneurs involved have requested anonymity until the deal goes through.
"They're used to whatever they go for they get, and they don't want to be seen as failing in their country if they don't manage to secure this deal," said Nathaniel.
Newcastle have appointed investment bank Seymour Pierce to handle the sale.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.