This is true, but if he had documented anything then he would have become significantly more replaceable. So replaceable in fact that the company wouldn't have

This is true, but if he had documented anything then he would have become significantly more replaceable. So replaceable in fact that the company wouldn't have had to hire me at great expense and could have got a normal developer in to take over and continue. Maybe I'm just extremely jaded since my job is fixing messes left by people with more style than sense but I see striving for uniqueness to be a flaw in an engineer.