Wilson was a Cop and Cops are supposed to be trained to deal with and arrest people without killing them. If in fact Wilson’s life was endangered by an unarmed teenager then he was doing something wrong, or was incompetent. If that’s not entirely his responsibility then it’s definitely the department that is responsible for training and managing the Cops responsibility.
If a truck driver in my company does something unprofessional and kills someone I and the driver would be held responsible on at least some level. Letting the Cops off scott free is wrong whichever way you look at it.