[notyourday]

Yes, by following DMCA procedures Github stops being liable for its users copyright infringement actions (safe harbor). Should Github not follow procedures defined in DMCA, Github would be on a hook.

[koenigdavidmj]

I'm describing a form of malicious compliance. Is there a legal requirement that the request be a web form? Or is it allowed to provide only a mailing address?

[notyourday]

It can be anything that provides a commercially reasonable way to contact the entity. So fax/p.o. box/email/web form etc all work.