I'm not sure I'd go that far. They blew it--yes. But they have been under extreme duress for over a month now, and they were undoubtedly at their breaking point. There's no telling what they've faced following Katrina, and they were probably a little trigger-happy because of it.
I'd say a short term of suspension without pay, lots of training in "necessary force", and of course, monetary retribution to cover the man's medical expenses.