But he would have to prove that the editing was done for the purpose of slandering him. That isn't going to be easy to prove.
But having said that, I think Zimmerman should push ahead with his suit. The odds are that NBC will settle rather than take the chance of a trial. Unfortunately whatever he gets will probably be eaten up by his legal bills from the trial and the inevitable Martin wrongful death lawsuit.
But by the preponderance of the evidence, not beyond a reasonable doubt. A lesser standard.