"I will not allow the good name of the Labour Party to be undermined by the behaviour of a few individuals," he said.
His solution was to use the Falkirk fiasco to reform the link between Labour and the unions.
On Friday, Labour announced that the two Unite members suspended over the Falkirk debacle had been reinstated.
This was because the "key evidence" about members being signed up without their knowledge had been "withdrawn". Without allegations, the investigation died.
The mystery of the vanishing allegations is the latest twist in an already murky episode.
It also raises fundamental questions. Why did the people who made the allegations withdraw them? And were the complainants contacted by anyone after they initially contacted the party?
Michael Crick, the political reporter for Channel 4, tweeted on Friday: "Falkirk Labour source claims witnesses to wrongdoing were persuaded to withdraw their evidence under pressure."
Last week's surprising turn of events confirms the need for Labour to publish its initial report into the allegations. By doing so, the public will learn about the original allegations.
Instead, Miliband's summer of silence on Falkirk has resulted in his tough words turning to dust. On several fronts, the Labour leader now looks vulnerable.
Prime Minister David Cameron is inevitably going to claim that Miliband has capitulated to Unite, while his trade union reforms also look to be in trouble.
His colleagues are also beginning to turn on each other, such as shadow defence secretary Jim Murphy and former deputy chair Tom Watson.
Rather than looking like a Labour leader who takes on vested interests, he may be cast as a puppet who capitulates to them.