FWIW: My fork is now back up -- I got a friendly support email from GitHub, and based on their suggestion I opened a support ticket to have them delete my current fork/url and then I simply reforked the original repo.

I guess this is best outcome one could expect from dealing with such a situation xD

Yeah, my fork of the original also shows the same never seen before repo as source: https://github.com/ppawel/youtube-dl

(Unless I'm missing something) you can't even delete the dcma'd one in the repository settings to clear up the repo name again :/