You must have missed the testimony from the two professors who had Zimmerman in their classes, and also the fact he had a CCW, which requires training and certification. I can understand your ignorance of that if you have an anti self-defense belief. I don't think any amount of "training" would get you to agree a man has a right to defend his neighborhood as well as himself.
If he has regrets about doing this, maybe a few because he put his life at risk for the benefit of people like you who wouldn't even come to his aid, and instead snipe at him from your Monday-morning quarterback seat.
Listen, i'm just glad that you're able to see a silver lining in all this for Zimmerman. Maybe, someday, he will, too.