Sounds bizarre.

I really don't know anything about it, but I do remember a call with nick [at] nickvsnetworking.com some years back and everything about that conversation was reasonable.
Isn't it simply a case of reaching out and asking for the license terms to be clarified, I'd be surprised if the response were to be silence or even negative.

(OK I really must learn to stop being surprised by what I'm surprised about, they way the world is.)

Is this simply some situation where Nick has not understood the conundrum in which the German law-abiding citizen is placed due to a lack of explicit statement of licensing terms?

Also, (and here I thought I understood correctly), but you may know better; Github's terms of service:

5. License Grant to Other Users

Any User-Generated Content you post publicly, including issues, comments, and contributions to other Users' repositories, may be viewed by others. By setting your repositories to be viewed publicly, you agree to allow others to view and "fork" your repositories (this means that others may make their own copies of Content from your repositories in repositories they control).

If you set your pages and repositories to be viewed publicly, you grant each User of GitHub a nonexclusive, worldwide license to use, display, and perform Your Content through the GitHub Service and to reproduce Your Content solely on GitHub as permitted through GitHub's functionality (for example, through forking). You may grant further rights if you adopt a license. If you are uploading Content you did not create or own, you are responsible for ensuring that the Content you upload is licensed under terms that grant these permissions to other GitHub Users.

Are German user's of Github somehow excluded from this global right to fork?

I know Mexico updated copyright law over the last few years, but maybe this implicit exclusive copyright if not claimed is not the same here, I could ask.. but I think best to reach out, no?

k/