It’s relevant, but I think I might have to preclude it 
– I think I’m increasingly convinced that this PEP is not the right approach: PyPI’s deletion policy arguably falls entirely under PyPI-specific policy (similar to malware/AUP/etc.), and I’m no longer confident that it makes sense to have a PEP that defines the minutiae of PyPI’s policies like this one does.
I think the conversation around quotas makes this clear: I don’t think this PEP can assert a normative solution to the quota “problem”, since it’s (1) entirely a policy concern For PyPI, and (2) the admins (IIUC) see existing solutions are largely acceptable (those being the support system and organizations of both types). Given that, I’m inclined to withdraw this PEP and treat this as a PyPI-specific problem for future efforts.
Sorry if this is not a super satisfying response! I agree with your comments about being able to express deletion across multiple indices, but I think that kind of policy communication might be better suited for an entirely new discussion and/or PEP that focuses on letting indices communicate what they do rather than attempting to assert their policies through the standards process.