Unfortunately the way the DMCA is written means that GitHub is acting prudently here. If GitHub does not take down content they receive a valid DMCA request for

Unfortunately the way the DMCA is written means that GitHub is acting prudently here. If GitHub does not take down content they receive a valid DMCA request for, they lose their safe harbor and can be made a defendant for a future frivolous copyright suit. Nobody should be taking flak for refusing to become a party to someone else's litigation.