He was _that_ bad really?
Theorem: when your former sysadmin can't hide his track better than that, you *know* this pink slip was not wasted paper. Corollary: don't fire a good sysadmin...
Corollary's corollary (in the light of current economics): don't hire a good sysadmin in the first place. Crap, this is getting complicated. Looks like they made the good decision: hire only crappy sysadmins, then sue the hell out them if they misbehave. Your systems might be vulnerable, but you will get your money back. C'mon, you know it (almost) makes sense.