Did he accuse them of misconduct? Why would they not say they called them both in since you contend it was ordered and they both showed up?
The only reasonable analysis is that Giobbi is full of himself and wanted to take credit.
Is your comment here a joke? Are you claiming the person who nearly admits to planning and staging a procedurally illegal interrogation will accuse the police who carried it out for him of misconduct?
The police are protecting themselves against some hypothetical honest Public Minister.
Giobbi's statements about the interrogation are not as you believe. For instance, he acknowledges that Amanda Knox had an emotional reaction during the interrogation, crying and screaming. This does nothing to establish his reputation (among reasonable people); it does show that the interrogation had unpleasant and coercive elements. This statement is backed up by statements from Raffaele in his book.
The lower ranking (Pergian) police apparently deny Amanda was treated harshly, threatened, or hit, yet she claims she was. Does that indicate to you that those police are credible and Amanda not? Do you thus agree with PM Mignini that Amanda committed criminal calunnia against the police?