I'm not sure about this kind of thing. Is this material that he wanted released to the public?
I saw an exhibition at the Brooklyn Museum several years ago of unreleased Marilyn Monroe photos, some of which had a big red (transparent) X over them, indicating that she'd asked the photographer not to print or distribute them.
I know how my paintings look when they're unfinished, and I'd hate for them to be on display in a state that I didn't want seen.