Wladimiro De Nunzio is a riddle.
He did not have the power to remove Sergio Matteini Chiari, but he was able to force him to step back through a machiavellian chess move, which we can say included a practice of ostracism and blackmail; and it was totally unjustified and unexplainable (to me).
The simple problem is, I don’t have evidence on Wladimiro De Nunzio. He is not an outsider and a discredited small fish like Hellmann and Zanetti.
Moreover, Manuela Comodi had arrested - while in Spoleto - a right-wing politician, a very close friend of Hellmann. They all knew about his resentment, de Nunzio too. The fact that De Nunzio’s role remains in the dark is probably partly a consequence of a Galati’s mistake.
Comodi (and Mignini) understood the trap and wanted to impeach Hellmann and Zanetti on their first wild words at the beginning, but Galati - who as a newcomer had just arrived from Rome - was probably afraid, as he understood the gravity of the situation, about waging a total war against the head of the appeal courts as a first step.
So he did not impeach Hellmann and his court; thus De Nunzio remained in the shadow. This reluctance or caution by Galati was the mistake.