I don't see what the big deal is if Harmy doesn't share something he was asked not to. Sometimes sources pop up that can be invaluable in a project you're working on, but only agree to let you use what they have if you agree not to share it publicly. The public still benefits from YOUR project, they're just not privy to the source to which you were allowed access. And it would be morally wrong of you to share the info when you were only given access to it by promising not to spread it. This isn't unique to Star Wars preservations. This kind of thing happens all the time in all sorts of fields.

And there's often very good reasons to not want the info shared publicly. It's not just so they can hold it over you that they have something you don't. I've been privy to information before that i KNOW other people would love to hear, but i'm not allowed to tell them. Sharing that infomation publicly would have very likely gotten the source in trouble or worse at work. Sharing it would also have cost me the source, who also provided a whole lot of information that I COULD share publicly & will likely provide more information. Why would I share the bits I was asked not to & jeopordize the rest?