Further, the reasonable-man standard of believing yourself in danger of bodily harm is that three elements must be present: Opportunity, Ability, and Jeopardy/Intent.
-The subject must have the Ability to do you harm.... okay, both Z and M qualify in that regard.
-The subject must have the Opportunity to do you harm right NOW.... if Z was walking away from Martin, this puts Martin's supposed SD claim in serious jeopardy. Contrariwise, we have an eyewitness that Martin was on top of Z, and Z had injuries of some kind.
-The subject must demonstrate Jeopardy behaviors or Intent.... the subject must do things
indicating that an attack is imminent, like cocking a fist and moving towards you, or verbally threatening and reaching for a weapon, that sort of thing. Again, we have eyewitnesses saying Martin was beating Zimmerman, but we have no eyewitnesses that say Zimmerman exhibited Jeopardy behavior towards Martin.... unless you count following him and keeping him under observation, and if that is ALL then we're REALLY opening a can of worms for people to make spurious SD claims!
Available info indicates that Martin moved to confront Z and backed off when he saw he was on the phone (to 911). Do we have any evidence that Zimmerman directly confronted (provoked) Martin? Not that I know of, other than following him, and that isn't a crime in itself, unless we start making assumptions
about Z's body language or facial expression.