There is no evidence that he sought a confrontation. I just think, carrying a concealed weapon, he should have stayed in the car and not put himself in that situation. Of course, he has the right to get out of the car and to talk to or get a closer look at whomever he thought looked suspicious, but is that the wise thing to do? IMHO, no.
He got out of the car because 911 wanted a street address. “Around the corner from the club house” wasn’t good enough. He got out to find a street sign.
But assume, arguendo that he did get out of his vehicle to see more closely what Martin was up to: How is that a criminal act or an element of a criminal act? How is it an element of manslaughter, even were the judge to get away with injecting manslaughter into the case at the eleventh hour, after the defense had presented its case?