If it's been proven beyond a reasonable doubt that the drive contains CP, then why don't they just go to trial? It seems to me that they've intentionally chose

If it's been proven beyond a reasonable doubt that the drive contains CP, then why don't they just go to trial? 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?