I would also observe that given the constraint that the customer doesn't want to actually give out their private key (and nobody should be willing to give it out, really...), this is the minimal possible maintenance burden they could possibly incur. Yes, the customer has to do something, but we already take that as a given when we say we won't hand out the private key. If the customer wants to have the responsibility, being able to reduce that cost to the bare mathematical minimum is a big deal.