I might be wrong, but I believe the "point" our friend is trying to make is that (in his or her subjective - and just possibly confirmation-biased - opinion) this photo of Knox, taken mid-afternoon on the 2nd November 2007, is some sort of visual evidence that Knox had not taken the shower that she claims to have taken at the cottage earlier that morning. Ergo Knox is lying about having taken the shower. Ergo Knox was a participant in the murder of Meredith Kercher.
Objectively, I would argue that this photo (along with all the others taken of Knox that afternoon) shows absolutely no evidence to challenge or contradict (or, for that matter, to confirm) Knox's account of having showered in the cottage at around 10.45am that morning. I would also objectively argue that even for a freshly-showered young woman, the escalation of events between 11am and the time when the photos were taken (probably around 3-4pm) would be more than enough to explain a degree of perspiration and dishevelment.
I suspect that if I took a shower at 10.45am on a given day, but then engaged in an increasingly worried search for my friend and housemate over the following two hours, then was present at the discovery of her murdered body, then passed through the intense feelings of horror, fear and grief following the discovery, that I too might have sweated more than a little and become a touch dishevelled...
