The dead perp in this incident was a black man who reportedly was shouting racial epithets prior to shooting the manager. You may be right in that shooting the perp before he shot the manager may have put the CCW holder in some legal jeopardy. But if I was on the jury and was presented a situation where an apparent crazed individual came in brandishing and screaming threats I might conclude that the CCW carrier may reasonably have felt in fear for his life.
The defendant would have my vote on that, too.