Do you think Zimmerman might have benefited from some training? Do you think it might have made sense for Zimmerman to enlist some backup from his neighborhood watch buddies before he followed a suspect into a dark area?
He was lucky to have survived his adventure that night, but only to then face jail, a murder trial, financial disaster, death threats, etc. I suspect he has some regrets.
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.