Ahh I see. It wasn't immediately apparent (to me, at least) that the line was there to delineate the Skype evidence from Guede's defence at trial.
But you've pointed out the very issue which may be of value to the defence. The whole point is that in his Skype call, Guede was very vague and generic in his description of the other people present at the time of the murder. He claimed that the man with whom he fought had a "non-foreign" (i.e. Italian) accent, and that he had mid-brown hair. He also only mentions the possibility of Knox's presence only extremely peripherally, via his ludicrous suggestion that it could have been her ringing the front door bell.
Yet - as you point out - by the time of his trial, this had all morphed into a very much more detailed recollection, in which Knox and Sollecito played definitive leading parts. And that's the important thing. Why did Guede's recollection of events seemingly improve by such a remarkable degree, the further in time he got from the night of the murder?
Why didn't Guede, for example, mention in the Skype call that Sollecito had a very distinctive Apulian accent (and dialect)? Guede was a fully naturalised Italian, who would undoubtedly have been able to recognise regional accents with broad accuracy - in exactly the same way as you or I (I assume here that you're British) could easily recognise a Scottish accent, or even a Liverpool accent, with very high accuracy. And since Guede claims later on (as you point out) to have been able to pinpoint Sollecito's accent, there's no conceivable reason why he wouldn't have been able to do so by the time of his Skype call. Yet instead, he offers a bland description that the man had a "non-foreign" accent. Doesn't fly, as far as I'm concerned.
And similar arguments can be made for physical recognition of Sollecito, and the whole placing of Knox into the scene. There's simply no good reason why Guede wouldn't have mentioned all this in his Skype call, if it were all the truth. Instead, all the evidence points towards Guede shoehorning Knox and Sollecito into his invented narrative at a later date, once he was in custody and he realised that blaming the two other people arrested for the crime was easily his optimum defence.
. So is showing how gullible someone is, especially when he/she boasts about his/her skepticism 
