that is an irrelevant case. a project that is breaking the law (youtube-dl project) will obviously be removed from anywhere on the internet. but this has nothing to do with bitcoin.

to answer your question, bitcoin is not hosted on github to need backing up. bitcoin is a protocol for a decentralized network.
each project implementing this protocol usually has multiple developers and many users. almost all developers have local backups and some of the users also create backups of their favorite projects. in case of any unexpected incident it wouldn't be hard to recover those projects.
but as far as i'm aware since there is no real "danger" there is no serious efforts.