Hold the phone. You're assuming all of this is public work. There are 12k somethings that haven't been released. What are they? Papers? Emails? Datasets? TFA doesn't say, and you don't know what they are either.
If they're his emails, then they are not public work and should not be released. Full Stop.
If they're papers, then a case can be made that they should be released. That said, all researches have work that isn't for public consumption. I'm a researcher at a public university. Do I have to publish my notebooks? How about every little piece of test code I write? What about works in progress? Some of the "papers" mentioned probably fall into these categories.
Without more information on what hasn't been released, we can't yet draw conclusions .