I followed this discussion carefully and I don't want to open wounds begining to heal, but as Judith encouraged all parts of the community to participate in this discussion I wanted to give my two cents.
The mere thing I am concerned is what message should we as mappers, modelers and creative folk take from this discussion when it comes to building upon other people's work?
As I understand some of you (mainly Spring and Judith) are not very happy to share their work if others can then re-adapt re-use and alter the work.
However if I understand the terms of the CC-BY-NC-SA 3.0 license under which TDM (along with all its assets and maps i assume) is licensed correctly then tdm maps and assets can be re-used and adapted without the authors explicit permission. All of you tdm authors granted these rights to everybody by releasing your maps and assets under this license. Of course anyone building upon your work will get these rights only in the case that he or she accepts to Give Attribution to the original authorsDon't use the work in a comercial contextRelease his/her derived work under the very same license and conditionsCorrect me if I'm wrong but the only violation (if at all) I can see in this affair is that Biker did not attribute Spring in the first place. Please consider that we are not talking about an officially released mission that is sopposed to be shipped with readme file, where you attribute people whose work you've adapted. It's a mission in beta test not ready for release yet. So I still disbelief that Biker's behaviour violated the license terms.
The problem I see is rather a moral issue. People in this thread have pointed it out: It's uncreative, it's discouraging for the original mapper who put a lot of time and blood into creating the map. And asking the author for permission surely wouldn't have hurt. Most of the times original author and adapting author will be able to find some sort of agreement on which parts can be re-used under which conditions.
But in some cases the problem might persist and that's why all of you (current and future) author must ask yourself if you want to build an tdm fan mission knowing that people may re-use your work without asking you explicitely for permission. It might sound harsh, but if you are not happy with seeing your missions and assets re-used, releasing your work under a Creative Commons license might not be the right thing for you.
I've not released a fan mission yet and cannot understand how much work has to be put into it. So veteran mappers might have a different view. But I personally think I would be happy if other people used my mission to build upon provided they do not apprpriate my mission but leave a thank you note for me in their release notes and share their missions alike.
The ability to re-use other people's work is what makes Creative Commons and Open Source so great. Don't give up on this easily.