Simple.
He was reporting a suspicious person? To whom? The 911 operator? He already did that.
You skipped over the part where Zimmerman approached Martin and asked him what he was doing in the neighborhood.
I’m sure Martin was not polite, and I’m also sure that Zimmerman wasn’t being very polite either. If Zimmerman was being polite, he would’ve of been the bigger man and walked away.
There is no question Zimmerman got his butt kicked, but that tends to happen when you think you’re some kind of pseudo-cop and start demanding answers from random people about why they are walking down a street.