I heard that story a while back and it was clear that the fact he had a gun in his car had no bearing on the outcome of that incident! The article I read indicated that he didn't even manage to retrieve his pistol from his car before the police turned up!
Only posting because I happened to spot this the other week so not making comparison to situation:
http://www.theblaze.com/news/2017/09/25/meet-the-good-guy-with-a-gun-who-stopped-a-mass-shooting-at-nashville-area-church/