I don't know who is more stupid, if the company or the IT guy

First of all, backups and documented settings. They might have taken a hit, but if they've had backups and the setup correctly documented, they could have gotten all this shit back up in a short period of time. Yeah yeah, I know, most companies won't backup the OS drive, still with a nice OS deployment tool and the backups, you could get everything back up in a short period of time.

Now about the IT dude.

He can argument that it was the heat of the moment, but come on, let's face it, after a hit like this goes down, the first people they'll look at are disgruntled employees. You should be smart enough to not do this from any location near your place, and specially not a few days after you were fired. If you know people on the inside (co-workers), just have the new password sent to you and do it on a trip, like 5 states away from where you live at....

You'd assume that an IT guy would be smarter than that....but well....guess not.