Either Terry Tao is - imprecisely and inaccurately - using the name of the popular git repository hosting service "Github" as a synonym for the open-source version control system "git", likely because he has some familiarity with software version control but is not himself a specialist in computer programming; or he does fully understand the distinction and Palomar was written in such a way that it only works for git repositories hosted on GitHub specifically and Tao is accurately describing that. Either possibility is unfortunate. I do not like GitHub's de-facto mindshare monopoly on decentralized version control system hosting.