IT admin people have the keys to the building and pretty much all data at the end of the day. Trust is everything and reputation is extremely important. This will not go well for the ex-admin one way or another either by lawsuit or blacklisting.
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.
At the core, IT people are usually seen as cost centers and not revenue generators. Not that I disagree with the business owners a lot of the time because IT is usually not the thing that makes a lot of companies money.
