Yes, and I think this whole case is needlessly complicated by people picking over the circumstances leading up to the actual shooting. They're all moot, because he hadn't done anything to warrant being confronted the way he was. For the sake of argument, suppose some stranger approaches you with a shotgun in the street and demands you stay where you are? What is the extent of your right to defend yourself against what is an unlawful act? Trying to grab the gun might be foolish, but does it give your would-be false arrester the right to defend himself by killing you? In fact, under that scenario, you are the one defending yourself.
In Georgia, "A person is not justified in using force...if he...initially provokes the use of force against himself..."
It was an illegal stop.