It's really not difficult at all to understand.
Sollecito can only be responsible for his own actions (and non-actions: e.g. not participating in the Kercher murder). He is not responsible for Knox. It is not his place to argue for Knox's innocence - it's purely his place to argue his own innocence.
The fact remains that it's still just possible - in theory - that Knox might conceivably have (for reasons unknown) chosen to steal Sollecito's keys from his pocket while he was sleeping/dozing, gone out and participated in the Kercher murder, then crept back into Sollecito's apartment and replaced his keys. Sollecito cannot say with 100% certainty that this did not happen. For obvious reasons. But he can say (and has said, repeatedly) that he doesn't believe Knox had anything to do with it either.
It baffles me how a large proportion of pro-guilt commentators cannot (or will not?) see the real picture here. Frankly, anyone in Sollecito's position would be strongly advised to take exactly the same line. Of course, if one is predisposed against Sollecito and Knox, then I guess it's all too easy to let the combination of poor thinking, vindictiveness, anger and wish-fulfillment cloud the judgement..........
The thing which makes the separation strategy (potentially) effective, is the provisional-judicial truth (most clearly written by Nencini) that evidence which implicates one implicates the other.
IIUC Nencini said this in his motivations report, because Bongiorno made this point at trial.
Once again, if the pro-guilt-lobby would bother to read Raffaele's appeals document to Cassation, it is spelled out there.
One of the issues of separation is where it was Amanda took the text/sent the text from/to Lumumba prior to being seen at Raffaele's by Jovana Popovic. Yes, prior to being seen.
It is telling that guilters are now doubting Nencini's brilliant grasp of cell-phone tower evidence..... but let's say that Knox actually did leave Raffaele's before Jovana Popovic saw her back at the apartment. Nencini does not use this to prove that Knox left afterwords, only that Knox was lying in saying that she never left the apartment that evening or that night.
The separation strategy should settle it for Raffaele, except that Nencini (equally brilliant as with his cell-phone analysis) says that this also is evidence against Raffaele. What Raffaele is asking about this (and other stuff they throw at Amanda) is: what's any of this got to do with me?
That's the question he's been asking since his own interrogation Nov 5/6, 2007. Of course guilters are going to accuse Raffaele of throwing Amanda under a bus with this: this is what guilters do and is what the pro-guilt lobby is for.
But the separation strategy is only indirectly related to whether or not Amanda managed to sneak out in the middle of the night unbeknownst to Raffaele. The reason Raffaele
**knows** she is innocent is as outlined in his book. There is no way she'd be able to get back in without him knowing.
As well.... the timing doesn't work. He knows he was not in the square to be spotted by Curatolo. Also, because Raffaele understands the time-line necessary for the crime to have taken place, Amanda would have had to have left the apartment (presumably by herself) well before they retired for the night, for all the other time-line related reasons....
...... a time-line most guilters refuse to put together, for obvious reasons.