I understand what you're saying, but I would't call it a "minor technicality" to shoot somebody in the back. A BP agent is only supposed to shoot somebody who is an immediate mortal threat to the agent.
The only mistake they made is wounding him and not killing him!
They shot him in the ass not the back. If you ever get a chance to read any arcticles by the renouned gunfight expert Mossad Ayoub you will see that such a shooting may have been entirely justified.