Not just that: indescriminate murder has never been Naofumi's thing. Wrath and vengeance when he knows he can go for it, sure, but what seperates him from Sword for example is that he properly thinks things through and considers the people in the world to be actual people rather than unimportant NPCs, it's part of why he hates "trash" and "bitch" so much for not only how they treated him but others in their own world all for selfish reasons; and those two are good examples of people he could have killed but did not for reasons. Naofumi's anger and pain has made him extremely untrusting, bitter, and prone to violent reactions; but not evil or stupid (maybe it's different in the novels, I wouldn't know). At least that's been how I see the character.