I think the point here is that this Teenager thinks that the punishment for not handing over the password can't be as long as the punishment for proving a crime using the evidence stored on his harddrive. I didn't go to the link, but from what I remember, he's accused of possessing child porn. In US, it would be as easy as saying, I've been under so much duress because of all this, that I forgot what the key is and where I kept it. I mean, they can't keep him locked up forever, right.
And that's the magic phrase right there. Along with "Terrorism", "Drugs" and "Rape", "Child Porn" is a bogeyman which many people feel justifies a reduction in rights of a serious nature.
Are they right? Well, that's not something I'm going to speculate on, but I believe the judicial system will push as hard as people expect/will permit them too. If the encrypted data was stolen e-books, I doubt they'd be so very harsh.
I think it's bollucks, however. I think you should have no punishment for refusing to help convict yourself, regardless of what you may have done.