Ultimate blame for this idiot's actions belong with the idiot. No doubt about that. Still, the article says it took a considerable time to physically remove the guy from the premises, and there was time spent for the idiot to get home. The manager knew HOW to change system passwords. Obviously the guy was not happy about the change in employment status, and the IT manager should have gone right to his desk and started changing passwords to every system as fast as he could do it, instead of trying to help get the guy outside. Its Texas, I'm sure they had some good-ole-boys in the manufacturing plant that power-lift pickup trucks for a hobby; they could have called upon for help.
The manager failed to close and lock the proverbial door. Doesn't make the SA in the right because he used it, and who knows - maybe the SA had backdoor accounts to use if the normal ones were changed. Still, the manager didn't implement what should be standard process - whenever anyone at a senior IT level leaves, regardless of circumstances, you change *all* the passwords immediately. Even if the guy left because he was "of a certain age" and leaving only because of mandatory retirement guidelines, he shouldn't be out the door before someone was busy changing passwords.