The evidence says otherwise.
He may have gotten carried away, but it was most definitely not by fear.
If the stories of suffering a series of previous breakins is correct, I could definitely see him snapping under a variation of PTSD.
Still doesn’t validate his actions as being either rational or acceptable. Or defensible as something a person can legitimately do in either a moral or legal sense. It just means that he gets to live out his days in a high security psychiatic facility rather than with the hoods in maximum security gen-pop.
It also is, as someone said earlier, a good object lesson for wannabe home invaders: you really DON’T know what’s waiting for you on the other side of that door or window ...