Mr McLeish, who was appointed first minister after the sudden death of Donald Dewar in 2000, but was forced from office after just a year over a personal financial scandal, also raised concerns about the ability of the Holyrood committee investigating the government’s actions to complete its work before the Scottish Parliament breaks for the election campaign on March 25.
A former MP before he was elected to Holyrood, Mr McLeish resigned as first minister after he was found to have sub-let part of his tax-subsidised Westminster constituency office without registering it in the Commons register of interests.
He pledged to repay the £36,000 rental income and stood down, to be replaced by Jack McConnell.
He said the contrast between the pressure on him to resign and the current situation where no-one had resigned despite the “huge cost” to taxpayers and the lack of resolution for the two women, was stark.
But he also said he believed the evidence given to the committee did not amount to a resignation matter for Ms Sturgeon.
"Her performance in front of the committee yesterday was what you would expect,” he said.
"She’s very skilled and good at messaging. She seized the moment, in a sense, because Alex Salmond has made such fantastical allegations about conspiracies, and she was able to continue her message that he had provided no evidence to prove them.
"I think the Conservatives have been quite foolish in saying they had found her guilty before she gave evidence and want her to resign. The evidence does not point to that. But there are still issues to be resolved, that is quite clear.”
Mr McLeish added: “I do find the lack of resignations quite bizarre. In a sequence of events you can normally identify where the fault lies, where things went wrong. The bill for this botch-up is huge, but it is clear the head of the civil service has neither offered her resignation nor has there been any consideration that she should do that.
"It astounds me that no-one has taken responsibility or been removed from office. And while the First Minister has apologised, it appears she’s protecting people, maybe out of loyalty, but that cannot be allowed to prevent the necessary actions from being taken.”
Mr McLeish said the coming dissolution of Parliament for the May election put the committee under huge pressure to have its report and recommendations concluded.
“If they don’t, then we are left in limbo and it will be the court of public opinion in the election which will decide things, and then if the SNP is returned the momentum will be lost,” he said.
He said the whole situation had thrown up issues about sovereignty of Parliament and the over-reach of executive power, and “after 22 years it’s time for substantial reform” of Holyrood as well as reform of the electoral system.
Mr McLeish also praised the committee for its focus “with one noteable exception”, referring to the lengthy questions put to Ms Sturgeon by Scottish Conservative Margaret Mitchell.