What you said earlier doesn't imply anything about derived works; just that the original goes on: "The only things you can't do are deny access to that which yo

What you said earlier doesn't imply anything about derived works; just that the original goes on: "The only things you can't do are deny access to that which you were given for free from the next guy, or scrub the existing credits to pretend you wrote it." Now you're saying you can't keep private what you added, which is a change. Google paid billions for the duplicated Nix library and then gave it away under a more permissive license. (That can't be said of all of Android, we agree, but I didn't mention all of Android.) You can't give everything to competitors all the time in business, in every circumstance.