The missing case here is what happens if they don't respond?
That (and when there is no author contact details) is when a unilateral process *is* needed. In those cases, I'd argue that we should have some overall guidelines to work from, but ultimately the PyPI admin(s) should decide on a case by case basis.
If and when the volume of such requests gets so great that the admins are overwhelmed, *then* we should look at the feasibility of an automatic process.