From this article, I take that judge McCreath acknowledged that Mangham did not intended to use the data he downloaded. Yet, he talks of "stealing" and "creating a risk" (a huge one, given Facebook's size). But really, how risky is it to keep data in an external hard drive at home? There is a risk, but I'd say not much. Also, there were no theft, since Facebook did not lose any data. And since this "intellectual property" has not been used, Facebook didn't lose a penny over this unwanted duplication.
From there, I see only 3 possibilities: (i) judge McCreath did not actually trust Mangham's alleged intentions (I'm not sure I do either), or (ii) he doesn't know enough about computer security, or (iii) other actual damages warrants the sentence (like wasted effort at Facebook's and by the law enforcement).
I bet judge McCreath wanted to punish Mangham over (i) and (iii), but it was easier to use (ii) to do so. Or, he doesn't really understand computer security, though that's less likely by the year.
From there, I see only 3 possibilities: (i) judge McCreath did not actually trust Mangham's alleged intentions (I'm not sure I do either), or (ii) he doesn't know enough about computer security, or (iii) other actual damages warrants the sentence (like wasted effort at Facebook's and by the law enforcement).
I bet judge McCreath wanted to punish Mangham over (i) and (iii), but it was easier to use (ii) to do so. Or, he doesn't really understand computer security, though that's less likely by the year.