At this point we can't even be sure they actually did break in his home. He might have killed them somewhere else, or forced them into his home at gun point. With what we know so far, its not beyond the realm of possibility. We don't know anything for certain after what he has said and done.
What I do know for certain, is that the firearms community should condemn this man, even if his version of events is true. Once a threat is neutralized you stop shooting. No if ands or buts about it.
"No free man shall ever be debarred the use of arms."- Thomas Jefferson