Jeremy Corbyn
“I don't see the circumstances in which that can happen," the Labour leader said.
The former cabinet minister says it "has not been decided yet" whether he will make a Commons comeback.
The party hopes a series of structural changes will repair the relationship with Black members after the report found racist attitudes to some MPs.
The pro-Jeremy Corbyn organisation's "very future is at stake".
Matt Zarb-Cousin said democratic socialists were "no longer welcome" in the party and urged others to defect.
The shadow health secretary insisted he made the comment "in jest".
An attempt to pave the way for Corbyn to stand as a Labour candidate at the next general election was defeated.
Party now has 432,213 members compared to 564,443 in 2017.
The former leader has been criticised for an appearance on Al Mayadeen in which he questioned the decision to send military assistance to Ukraine.
Friends of the former Labour leader want him to establish a new 'power base' for his progressive politics in the capital.