it should be noted that afaik, nobody has died from BLM protestors so a “fear of dying” in the encounter should indicate a deeply troubled mind. So a competent prosecuter could probably have convinced a jury that Kyle’s fears were largely irrational and could have probably stuck manslaughter charges on him.
After all, if you start marching around with a gun in front of your neighbor’s house then shoot him when he approaches you yelling to get off his sidewalk or whatever, its a bit insane, if not premeditated.