The only patron that appeared to be in danger was that woman who plodded right past the gunfire, hands over her ears. It made me wonder if she understood what was taking place around her.
But I don't think she was ever in the line of fire, so long as she didn't suddenly jump to her left. The old guy was very concentrated and had a good Weaver stance. And the robber's gun was pointed at him, even though the robber's attention was diverted.
Looks like a good shoot to me, and the DA seems to agree.
The slimeball's argument that he was down and therefore no threat is bogus. Plenty of people have been shot by a wounded felon returning fire. You keep on shooting until you're sure the threat is over.