Sure, and when did a higher power give armed criminals kicking down people's doors the right to their tv?
As described shooting them in the back when they were leaving is legally a bad shoot. We don't know that's what really happened. Who cares about this "shooting a man in the back is cowardly" business in a home invasion? If there are two armed home invaders searching for me in my house and by the grace of God I find myself behind them I'm going to shoot. I for sure am not asking them to face meet me out in the street at high noon or some crazy thing like that. For all we know that was the case with this guy, too. Were they leaving, or just looking out the door to check for cops, a friend in the car, etc? Were they looking around for the homeowner, maybe working in the yard? News reports rarely get the fact straight or tell the story accurately. The macho/coward thing just isn't even a factor when somebody breaks into your house, and doubly so when they're armed.
As far as calling his mom goes, I could believe that. My sister was cleaning a house once and was affraid somebody else was or had been there that didn't belong. She was panicky so she thought to call me, not the cops, first. I don't see anything at all suprising that many people instinctively trust family members over strangers with an uneven hand.