SYG IS NOT APPLICABLE in this case. It’s pretty plain from the evidence that Zimmerman was being attacked. That invalidates SYG altogether. SYG allows you to confront someone where you would otherwise attempt to retreat. Zimmerman had no choice. He was already past the point of being able to retreat.
His decision to pull the trigger is permissible by Florida statute. He was using it to stop the commission of a forcible felony. Period.
Yet he got arrested, didn’t he?