Section D.3: "If you're posting anything you did not create yourself or do not own the rights to, you agree that you are responsible for any Content you post". A lawsuit against Github has no standing for the scenario you suggest, because Github is not at fault.
Ok, so: "that just means that GitHub as a service makes no sense, right?" Like, I feel you simply ignored the core complaint of my comment so you could instead note something about GitHub's potential liability (a thought process I didn't even bring up, though I can see how many you decided to bend my final comment into somehow being relevant for that thought). Like, are you simply ceding then that a ridiculous amount of the content on GitHub -- including major projects such as Linux -- are not allowed to be posted to GitHub?