I know they aren’t required to, but I remember the olden days when more companies would fight dmca requests. But I suppose they were much less common then.
The EFF might help, but even expecting individuals to appeal to the EFF is probably too much work and too much risk.
I’d like to see GitHub partner with EFF to have first look at these requests and choose to fight ones that seem invalid. I’d donate to they cause.
It probably doesn't make sense for Github to indemnify them, and short of that, there's not really a lot of convincing they can do if someone isn't interested in engaging in litigation with some huge company.