It seems to me anyone who's driving a car and tries to stop someone without benefit of a uniform and badge is going to get a fight. One reason I don't think undercover cops should ever be allowed to arrest anyone, arrests should always be made by uniformed officers. Undercover is for collecting intel, nothing more.
How do you know he tried to stop him. He called the cops and was following him. Is it against the law to follow someone? For the sake of argument, let’s say the kid saw the guy following him, got mad, and attacked the guy. During the struggle, the kid tried to grab the gun the guy was legally allowed to carry. Would Zimmerman have the right of self defense in this case?