So you can leave (because you don't really want to work in an organization that needs that kind of intervention).
Or you can speak to the co-worker, and try to come up with strategies for fixing shit. It doesn't sound like he's just angry (otherwise management wouldn't have his back), it sounds like he's angry at actual problem. Try to get him focused on the problems that can be fixed (see the Joel test?), not ones that can't (people issues).
Try to get him to focus on the process, not the people.
Or just leave. It's possible he's just an asshole.