Wrong, stand-your-ground was fundamental to the jury's eventual verdict:
COOPER: Because of the two options you had, second degree murder or manslaughter, you felt neither applied?
JUROR: Right. Because of the heat of the moment and the Stand Your Ground. He had a right to defend himself. If he felt threatened that his life was going to be taken away from him or he was going to have bodily harm, he had a right.
http://thinkprogress.org/justice/2013/07/15/2306631/zimmerman-juror-says-panel-considered-stand-your-ground-he-had-a-right-to-defend-himself/
And the only witness who said his head was being slammed repeatedly into the pavement was the guy on trial for 2nd degree murder. He had lesions on the back of his head but nothing serious. I don't believe Zimmerman, but I acknowledge he might be telling the truth and we'd never know. So should he spend time in jail? I don't know, it's a really complicated case, but i wish people would acknowledge for a second that GZ might be telling a lie to get out of a long prison sentence.