I don't think anyone questions that. Obviously lets say I write a book, unless I abandon my copyright its mine.

Now, the thing is, edits are different, requiring express written consent of the originator, herein I'm not sure whether a usage license qualifies.

Now, the question is, written consent of what? The US Dept of Copyright states the original author by default is the only person who can copyright a derivative work and others acting with his permission. You see what I mean? I still don't think the CF codebase is copyrightable because its a derivative work and I somehow doubt DIKU sent you something in writing to the effect of the above. Now, if they did, obviously that invalidates my point. But if they didn't, how sure are you that your copyright would hold up in court?