It wouldn't be React getting the notice. It would be say, someone forking React, then adding a pull request with some clearly DMCA-violating material.
Then, if downstream B DMCA shutdown doesn't affect upstream A's availability, there's still the question of A normally still having access to B's non-merged commits even in the case of B's deletion. So, A should still be access the DMCA-violating material.
And, if A's access to B's non-merged, DMCA-violating commit is truly revoked without affecting A otherwise... why can't we have a "Strong Delete" button on GitHub? Would seem they'd have to have "Strong Delete" functionality to comply with downstream B hitting DMCA.
Basically, I'm feeling either a violation of principle of least astonishment, or a violation of "strong-DMCA".
Unless this is to support a feature in Git/GitHub that I am too noob to understand. :shrug: