K. Law: "Leaders do not make their points at the expense of their best subordinates ... "
They do make points at the expense of their best subordinates but it's usually done in conjunction and with the knowledge of the subordinate. I've seen it done and it can be effective. In this case, however, I don't think Harper knew he was going to be used as an example (probably never crossed his mind) and he's not ready (mentally/psychologically) to accept that role. IMHO, Harper is not a leader of other players on this team. Williams didn't pick on one of the big boys. He picked on the weakest/most fragile link.
Williams blew his cool and lashed out. Hopefully, he'll learn something from this to become a better leader.