In other words, the immoral actions of one person justify the immoral actions of another person.
Two wrongs make a right.
I disagree with this analysis.
He chose to do evil in response to her evil act when he could have done good.
He could have defended his home and then called an ambulance.
He instead chose to commit murder.
Since you can't even grasp the concept of who initiated these events, please forgive us if your concept of what is "moral" is equally suspect.