Hopefully I'm wrong but I doubt that the police left this guy go scott free. If I was in this unfortunate situation, I think I'd try to cover the bruises and be damn glad to get out of there without anyone knowing. Of course, I wouldn't have ever had my wallet on me in this situation in the first place lol.
I understand the legal point that he didn't commit a crime but the hassle he could be put though could be almost as bad. Not to mention I wouldn't want the stories about it passed around between family members, colleagues, etc.