As others have mentioned, I believe that the main problem here is that youtube_dl is "showing intent" to violate DMCA. If they modify the readme, they might be able to prove that the intention of the software is not necessarily to violate DMCA, but maybe just being a general purpose code or one for educational purposes.

Regardless, it's possible to host PyPi wheels yourself if necessary. The installation process wont be as straight-forward as "pip install youtube_dl", but it's still doable with one command.