Nope, that won't work. Z was not standing... he was on the ground. His only shot is if Floriduh has a "lying on the ground getting the snot punched out of you, your nose broken, bloody head, and coming close to being killed" law.
The “Stand Your Ground” reference to FL’s self-defense law is somewhat misleading. “Stand Your Ground” is only part of the law. If Zimmerman can get vindicated by the judge in a hearing before a jury verdict, then no civil suits against him (or the city, or the homeowners’ association, etc.) are possible. And the standard in that hearing is just a preponderance of the evidence, not beyond a reasonable doubt. That's why the self-defense hearing is so important.