I would be reluctant also if you see how the witnesses are attacked in this case. It is true that he did tell his co-worker, Chiriboga right away that he saw Amanda that morning. The appeal court (CAA) does not mention the testimony of the co-worker and gives no explanations for leaving it out. It is part of the SC appeal.
Funny they don't actually quote her then. It would go against the police's testimony that he didn't mention her coming in after the murder, and also said he saw her and Raf before they had even met. He also says he wasn't shown photos of them and Chiriboga contradicts him on this, as does the police's testimony. Here are actual quotes.
The above example is merely the contradictory result of a partial reading of the testimony of the witness. Specifically, at the hearing of 21.03.2009 (transcript, p.83), Sollecito's defence asked: "The specific question is this. Did Inspector Volturno come with photographs of Amanda and Raffaele?" Quintavalle responded "With photographs, no, I don't think so". Inspector Volturno questioned about the same set of circumstances, however, declared "A few days later we tracked down the Conad-Margherita shop situated at the beginning of Corso-Garibaldi, where the owner recognized the photographs we showed him, Raffaele Sollecito and Amanda Knox. Raffaele Sollecito was a regular customer of the store, while the girl had been seen two or three times in his company" (transcript of the hearing on 13.03.2009, pp.177 and 178). Yet, on being asked "Did Inspector Volturno ask you if you knew Raffaele Sollecito and Amanda Knox?" Quintavalle replied, "About Amanda they didn't ask me, that is, they did not ask me if Amanda came to the shop" (transcript of the hearing of 21.03.2009, p.83). This fact was contradicted by the declarations from his assistant, Ana Marina Chiriboga, who, when asked by Knox's defence, "When the police came and spoke with Marco Quintavalle, they didn't speak with you the first time. What did Marco Quintavelle say about this interview? Of what did they speak?", replied, "Nothing, he told us that they asked him if he knew Amanda and Raffaele. Since we had already seen a bit on TV, so we commented" (transcript from the hearing on 26.06.2009, p.54). And again, to the question of the defence, "So they had arrived. What did he say?", "That he knew them", Chiriboga replied precisely, "Yes, ah, they wanted to know if he knew them? Him, yes, he said he knew them, but I said I didn't, also my colleague said that..." (transcript hearing 26.06.2009, p.55), and to the further question, "Quintavalle replied that he knew Amanda and Raffaele, yes?" the witness replied "Yes" (transcript of the hearing 26.06.2009, p.56). Therefore, we do not see how it is possible for the motivations to affirm that Quintavalle did not report to have seen Amanda Knox the morning of 2 November only because he was not asked" (pp 75 and 76 of the motivations).