Properly documented policies could have helped in this situation.
A policy should have been in place that defined who the business owner (management) of the resource was (network in this case). It is the responsibility of management to ensure that they define who has a business need for access (and have it documented), and it's the responsibility of the tech grunt to run the system (or network) for the business owner.
The key point is that as a non-manager type person, if management says jump, get it in writing and jump. Management is ultimately responsible for the system and network to the business. If management has made bad choices or decisions, it's their fault and if the request or actions leading up to the failure are documented, that admin can refer to that.
All organizations should at least have a documented policy of who can have access to resources and that the business owner of the resource can be easily determined. The business owner needs to be someone who is legally responsible to the organization (i.e. an executive, or someone high enough in management).
As a system administrator, you should insist on having this documented just to protect yourself. If you suspect that there is some management decisions that could jeopardize the operation of the system, document it, report it to the business owner and let them make the final decision (with documentation).
In the case of Terry Childs, had this been documented, he would have been able to either say that the person who was requesting the passwords did not have a business need (and would be able to back that statement with documentation), -or- if the person did have authority to have access, he could have simply have documented why it was a bad decision, hand the passwords over and walk away from it.
Yes there is a pride element. You've spent years building up a system and making it shine, but unless you are running your own business, you are not the legal owner of that system.