As for the (predictable) backlash against the guy who shot the bad guy...
I lend little, if any, credence to people who fall back on the story of what a Good Samaritan "actually" is or that Jesus wouldn't kill another person when they, themselves, are part and parcel to either denying the legitimacy of various religions such as Christianity or actively involved in the elimination/suppression of various values rooted in religions such as Christianity.
You cannot, on the one hand, deny/put down/denigrate such while on the other hand using those very same things to support your own views.
"He shouldn't, he shouldn't, he shouldn't..."
Well, guess what? He did. And lives were saved. It could have gone MUCH worse for a variety of reasons, but it didn't.
Make a decision and DO something. The road to success is littered with the squirrels who couldn't make a decision. This guy made a decision, and the consequences are something he'll have to deal with...from the simple fact that the deliberate taking of another human life will have a big impact on him personally, to the court of public opinion, to whatever legal issues may come his way over this. In a split second he made a decision that said "these people's lives are worth the cost to me".
These people aren't upset that this guy saved lives...they're upset that they don't have the full control over everybody's lives that would subjugate others to their own ideologies and will. THAT'S what they're upset about. They're upset that the "no firearms policy" does not carry the weight of law in Indiana (and other states). They're also upset that their belief in "no firearms" policies isn't what they think it is. They're upset that someone had demonstrated very publicly that ordinary citizens who carry firearms can, and do, legitimately use them for defense of themselves and others.