Some will argue that it goes against everything Salinger would want. e.g. He doesn't want to be "judged" à la "Catcher in the Rye". However, if he truly never wanted them to be read, he would have burned them immediately after being written.
https://www.nytimes.com/2017/10/25/books/jd-salinger-new-boo...
"But in 2013, a documentary about the author and a related book offered a bold assertion: He had not only continued writing, but also left detailed notes to his trust about releasing the material between 2015 and 2020."
To me it seems credible that a writer might want to hold on to some drafts, hoping to get round to editing them for publication, but doesn't want them edited by anyone else or published unedited. The question is, how to achieve that, seeing as one can't trust one's heirs? There are probably both legal and technical solutions.
https://en.wikipedia.org/wiki/Mortmain https://en.wikipedia.org/wiki/Rule_against_perpetuities
There's also the expression "dead hand", but that may also refer to a Soviet strategic defence system, which has also been referred to as "hand from coffin", which is certainly more fun than the official name.
Maybe he wrote them as practice. Maybe he wrote them to experiment with a new style. Maybe he wrote them to explore his thoughts and feelings. Who knows.
It does appear that he was okay with these things being published, but in the general case it’s not true that someone writing means they want or intend it to be published or even read.
Now, with digital distribution, once released, you can't put things back in the bottle (with a few exceptions like when Amazon or Apple do "recalls"), but for the most part, you can't undo things and that means authors have less control over what they produce. Maybe authors aren't allowed capriciousness anymore ("burn all my writings upon death").