It seems to me that they've intentionally chosen a morally-objectionable individual upon which to build a legal precedent, as anyone who speaks in his defense can have his crime thrown back in their face.
We've heard a lot about these so-called "hashes" that prove the presence of CP. It's also pretty easy to make a probabilistic proof about the likelihood of a hash collision between two non-identical files. I would venture that if you can show mathematically that you're 99.9999999% certain that the files are CP, that would qualify for "beyond a reasonable doubt".
It's incontrovertible that if he's committed the crime for which he's been accused, he should be jailed. If they've already proven that crime, then why isn't he already serving his sentence? Or does the prosecution's case rest upon this one piece of evidence, and if so, is he therefore required to testify against himself in order to avoid indefinite detention?
You call it a fortuitous decision, I call it precedent.
People have got to stop martyrizing this guy. He's in jail because the prosecution got a fortuitous decision that says they can hold him as long as they want until he coughs up a password. They aren't fishing for evidence, nor have they used this trick on anyone else. If he went to trial on the evidence already in public, the guy would hang (metaphorically). There is no significant doubt in anyone's mind that this drive contains CP.
But the principle is the important part you say? Sure. Make a principled argument. Don't cite this guy.