... lethal force may be used when such force is threatened by the bad guy. In this case, the bad guy drew a gun. At that point, the CCW holder definitely had the legal right to defend himself with lethal force. This issue at that point had nothing to do with the woman being in jeopardy.
The above is the crux... Short version is that 3 perps were on a multi-event crime spree and, of course, preferred that everyone "mind their own business."
In the video follow-up link above; The interview with the two sisters of the slain perp reveals their level of "denial" too... One of them says, "This is not Gotham City... He's not Batman." ... and then the voiceover says she adds that "robbing someone was wrong but not a reason to kill her brother..."
Well... He WASN'T shot outright for hitting the woman and taking her purse!
He was shot because he drew a gun on the "good samaritan". He had other choices available when the good samaritan encountered him; He could have given the purse back. He could have driven away. But he didn't. He drew his gun... And THAT was the new scenario that justified the shooting. The good samaritan didn't PLAN it that way... It's just the way events unfolded.