It's taken me a while to put the unstated argument into words: That a victim must accommodate an attacker's level-of-force expectations, letting the attacker determine the limits of defensive response. I feel that once the attacker crosses a certain line, the target of aggression has a basic human right to prevent immanent harm to self or others. I am willing to hear arguments about that line in terms of aggressive behavior, but I don't think it requires display of a deadly weapon. Every day people maim or beat others to death with bare hands or a convenient stick or rock, let alone with a knife or other weapon pulled only when the tide turns against them. Attackers have no right to get in a few licks on "fair fight" terms.

I still think this case, having no witness and possibly some contested facts, deserves to go to trial. But if the question is "given a aggressive attacker and even half a possibility of being tackled while running away, should the defendant have chosen other options?" I would say, no.