[brudgers]

It's not your job. It is management's. If it is not worth the risk of airing your concerns to management, then that just shows that it is not really the particular developer that is the problem. And the idea of "the team" taking matters into its own hands is just another sign of how dysfunctional the workplace is.

Either act properly, or don't act. There's no excuse for anything else. The internet cannot give you permission.

Good luck.