I would assume that "believed" is not meant to be interpreted in an active personal sense but in a passive configuration sense. That is, I'd expect there was a

I would assume that "believed" is not meant to be interpreted in an active personal sense but in a passive configuration sense. That is, I'd expect there was a flag in a database somewhere saying that those service accounts were "abandoned" or "cleaned up" or some other non-active status, but that this assertion was incorrect. Then they probably rotated all the passwords for active accounts, but skipped the inactive ones. Speaking purely about PKI and certificate revocation, because that's the only similar context that I really know about, there is generally a difference between allowing certificates to expire, vs allowing them to be marked as "no longer used", vs fully revoking them: a certificate authority needs to do absolutely nothing in the first case, can choose to either do nothing or revoke in the second case, and must actively maintain and broadcast that revocation list for the third case. When someone says "hey I accidentally clobbered that private key can I please have a new cert for this new key," you generally don't add the old cert to the revocation list because why would you.