Chris, I agree with most of what you say, except starting here:
He tries to grab you.
To the best of my knowledge, there is absolutely no evidence to support that Zimmerman caught up with Martin, or that he tried to grab Martin. Not on the 911 tapes, not from the statement from the girlfriend about her conversation with Martin, and to my knowledge that has not been brought up. I am NOT saying that Zimmerman's decision to follow (or chase, depending on what happened that night) Martin was a smart decision, nor a wise decision.
Currently, the media is beginning to report that the police report, or at least part of it, has been leaked. In said report, Zimmerman states that he was returning to his vehicle when he was approached from behind by Martin. The two exchanged words (unknown what was said, if any of it falls into the "fighting words" legal definition), at which point Martin punched Zimmerman once in the face, knocking him down, then got on top of him and began slamming his head into the ground. He also states that Martin tried to grab his gun. Quoting from Mas Ayoob's blog at
http://backwoodshome.com/blogs/MassadAyoob/2012/03/23/george-zimmerman-and-trayvon-martin-what-we-dont-know/ -
The death weapon was a Kel-Tec PF9 semiautomatic 9mm pistol. It has been reported that the gun was recovered with a full magazine and that only the chambered round had been fired. This is a condition we associate with something preventing the gun from cycling a fresh round from the magazine into the chamber after the shot was discharged. One thing that can cause that is another man’s hand wrapped around the pistol, retarding its slide mechanism. This would indicate, as could certain gunshot residue patterns or cuts in certain places if found on Trayvon Martin’s hand(s), that a struggle for a gun was taking place when the fatal shot was fired. This would clearly change the shape of the case. But – WE DON’T KNOW YET.
Now, the police have reported that what the Orlando Sentinel printed was consistent with their report of the investigation, and with the evidence they have passed on to the DA's office.
IF (again, we DON'T KNOW this yet) this was the actual series of events, then Zimmerman HAD disengaged from Martin, and was returning to his vehicle when he now was confronted by Martin. To me, this does not strike me as someone who was fearful for his safety. Martin had a phone. Why didn't he call 911 to report this strange dude following him around the neighborhood? To me, that is the reasonable course of action. Not returning and re-engaging the person you are allegedly afraid of. Again, we don't know what words were exchanged during this second encounter. But again, if these are the facts of the case, then Martin was the one who took the event from a verbal altercation to physical assault by punching Zimmerman. Other than a very specific set of "fighting words" a verbal altercation DOES NOT justify a physical assault. If he then got on top of Zimmerman and was slamming his head into the sidewalk, then Zimmerman did indeed have a reasonable fear for his life. And at that point Stand Your Ground is immaterial. He doesn't have an option to retreat, as he has his assailant on top of him.