Well, assuming he doesn't change his name and fake his employment history. Or just deny it. Or threaten to sue for libel if anyone claims it was him that did it. If it was me I'd claim they screwed up (restored a backup onto the backups, something like that, happens all the time) then blamed me. Let's be honest, they're more screwed than he is.

And yet, they are often abused, underpaid, and treated as replaceable. The only surprise should be that this doesn't happen far more often.