All of this is really troubling. The first thing I thought when I heard about this incident - who the heck GOES to a riot? WITH A RIFLE??? He drove 20 miles to get there! Where were his parents?
In a video of the shooting online - you can see Kyle running away from people chasing him. He trips and falls. One of the people in the video DID have a gun.
So here's Kyle lying on the ground (after trying to run away) and these people are still coming towards him. He might have been worried he was going to get beat up (which has happened to several people during the riot, including a 70 year old guy trying to put out a fire in a store). He might even have been worried he'd get shot, since one of the guys in the video had a gun. An argument can be made that he shot in self defense at that point.
The thing is - none of this would have happened if Kyle had just stayed home. Instead, he went looking for trouble, and he found it.