The remark wasn't funny. I agree with Tom Hartmann that it is a cultural issue. A Caucasian policeman attempting to inject levity into the situation is someone that is insensitive given today's environment of police shootings of Blacks proprotionately and per capita.
The officer has been suspended. He needs to be retrained before "hitting" the streets again. He probably needs to patrol with a senior Black officer that can provide him some insight into what the Black community experiences everyday in the Atlanta area besides the training.