Sure, it's an understandable trauma response. But it would be healthier in the long-term for him as the person experiencing it and especially for us as readers to understand that at the end of the day, it's just not true - not in the way that he wants it to be, anyway.
He understands that he had a choice, that's why he is trying to convince himself otherwise right now.
Honestly it's crazy that there's such debate around what happened here.
"If he didn't kill he would have been killed."
Well that's true but being killed is also a choice he could have made, what we should be questioning here is not "If Einar had a choice" but the morality of the situation:
- Is Einar wrong for killing those who were going to kill him?
Well, the answer depends of how much of a hardcore pacifist you are, some would rather be killed than to harm another person.
I saw some people commenting on how this chapter also paints a picture of how Thorfinn and Thors' brand of pacifism is only possible because both Thorfinn and Thors are extremely powerful warriors chosing not to do harm and that's also really interesting.