Crazy Little Thing Called Animal Justice

This story struck me as weird. In it, it details the sentence of a German Shepard to run guard duty at a prison instead of being put down after attacking a person.

I don't even know how I feel about it yet. I mean, I'm glad he didn't get put down, but the whole reason for criminal laws (or at least a main reason) is retribution and rehabilitation. The dog isn't going to know he's being punished. So the point is??? I guess sparing his life. It was a very creative move on the dog owner's part. I'm still on the fence.