It's called 'neighborhood watch' not 'neighborhood follow' for a reason.
The onus is also on you to demonstrate how anything Zimmerman did could in any way have compromised his legal right to self defense.
So far you have posted absolutely nothing regarding either of these.
And remember, the law does not operate under the principle of 'guilty until proven innocent' for some very good reasons, even if you do.
Possible/probable scenario: Zimmerman lost sight of Martin/retreated, Zimmerman was unsuspectingly jumped/overpowered by Martin, Zimmerman was on the ground getting pummeled/could't retreat, possible tussle for his gun which may have fallen out of holster or taken out by Zimmerman OR Martin, Zimmerman takes control and does the only thing he can at that point to not get shot himself.
OH...and following a person from a DISTANCE...and not even speaking to them? What law did Zimmerman break?