Well thanks for taking a crack at it.
The idea is based on Hellman's statement in the CBS article, that once Girlanda made the acquittal a political matter, he "knew the acquittals would be reversed".
Once we accept Hellman's view as accurate, then it follows that a cessation in the underlying political conflict between Burlesconi and the judiciary would naturally pave the way for a reaffirmation of the acquittals, which were unquestionably wholly merited.
The further backstory of a conflict between Mignini & Giuttari attempting to profit from their satanic hoax (by imparting a satanic sect affiliation to fill in the missing motive tying together the wrongfully convicted defendants Vanni and Lotti with Pacciani in the Monster of Florence cases), shows the factors that were constraining the judiciary from moving forwards (fear of undoing the convictions of Vanni and Lotti, the only convictions on record in the MOF crimes), and their intention of pushing back against Mignini in preventing him from ensnaring innocent citizens in his hunt for a non-existant satanic sect in his Narducci trail and this case Kercher case.
In terms of proof, short of recorded conversations, yeah, not likely to surface.
But I do think there's a fairly persuasive circumstantial case to be made, by virtue of the confluence of events. There seems to be a balanced choreography to these cases, the verdicts (Narducci Florence 20 and Hellman reversals in March 2013), and their proximity to one another (Burlesconi appeal- in 2014 - and final acquittal just in the last 2 weeks for his underage sex case). Very odd that they would all cycle through the courts, and come out in paired decisions that seem to tell a story.
Or, maybe I've been reading too many of Mach's posts, which is also a distinct possibility. I have to say about this, my view of a residual "responsible people Italy keeping this all on course" and Mach's view of a deep seated masonic conspiracy are two sides of a coin, much as I hate to admit.