Hmm they seem to be taking it from the approach that RIAA was sending a takedown on the grounds that youtube-dl was infringing on the copyright of their members, but that doesn't seem to be what the actual takedown claims. Instead it's requesting takedown on the grounds that youtube-dl is breaking protection measures in violation of 1201, and the answer given doesn't really address that except to say that breaking protection measures isn't infringement (which wasn't what they claimed in the first place).
EFF represented youtube-dl to get the repository reinstated, and their lawyers instead tried to prove that YouTube doesn't have DRM, and that the test cases provided were neither suggesting other people to infringe, nor infringing themselves (falling under fair use). The full response is here: https://github.com/github/dmca/blob/master/2020/11/2020-11-1...
EFF represented youtube-dl to get the repository reinstated, and their lawyers instead tried to prove that YouTube doesn't have DRM, and that the test cases provided were neither suggesting other people to infringe, nor infringing themselves (falling under fair use). The full response is here: https://github.com/github/dmca/blob/master/2020/11/2020-11-1...