The problem with the Amanda Knox case is not scale, but distance. The farther away something is, the less influence I have over it, and the less influence it can have over me. Amanda Knox is far away in every sense - it's in a different country, a different time (the court case is already over), and a different language. It's like watching a year old YouTube video of an already-fired policeman from a town I've never heard of abusing his power - lots of people do it, but it's just getting riled up for no reason.

On the other hand, the point of the original Less Wrong Amanda Knox article wasn't that we should care about the real event, but as a rationality test case. A similar fictional story would've worked just as well, but using a real news story guaranteed that it'd be free of the distortions that come with writing fiction.