That wouldn't have helped in this situation. The perp wrote software that ran when his account was disabled after he was fired.
According the article, it said the kill checked to see that his account was still in Active Directory, when it got deleted, the kill switch kicked in and did it’s damage.
What I’ve seen companies do is not delete accounts when get fired or laid off, the disable them just in case they have to be access at some point in the future, email is a perfect example.