[user104658]

There's a difference between morality and legality I think if what everyone needs to remember here. This case is of course HUGELY up for debate in terms of morality, you could philosophize over it for months.

In terms of the US legal system though? These states allow people to carry firearms, and they (often heavily) promote the ideas of full liberty of self/self defense by any means.

Whatever the circumstances, he was at genuine physical risk and he used a firearm to defend himself. Legally, the US allows this. Thus, legally, it's the "correct" result.