Earlier quoted context omitted.
There are other precedents I think. Here (Sydney Australia) the penalty for refusing a roadside alcohol test is the same as the top range blood alcohol penalty. So you can refuse a test, and they'll penalise you assuming the worst-case result you could have produced. I'm guessing this guy is in a quite perplexing quandary - he's betting on whether they'll keep him in jail for as long for refusing to decrypt the drive…
If he was using Freenet, there's no doubt that his node handled chunks of CP files, and that at least some of those chunks remain on the drive. Let's say that he never viewed any CP. Even then, can he be sure that investigators won't discover evidence that could be spun to demonstrate that he did view CP? It is quite a quandary :(
Might not help him if they believe that the encrypted keyless fragments is enough (which would be a horrible legal argument).