This is still an asymmetric, unfair process. Automatic takedowns from bad faith actors are catered to left and right but you have to negotiate a bureaucracy with manual review to get restoration. The DMCA doesn't require this to receive safe harbor protection.

Provide a form where an up to date contact point can be submitted that you can forward to the plaintiff and then restore the content. It's that simple. They can deal with litigating the dispute from that point on and Github is not responsible.