AC is not bound to be historically accurate.
“the game will ‘desyncronize’ you (meaning produce a game over) if your character kills civilians, including if, while raiding a monastery, you kill the monks. You are a viking (one thing they do right: viking is a job description, meaning ‘raider,’ not an ethnic identity) who does not kill non-combatants. This is akin to the famous joke about the pirates who don’t steal anything.”
https://acoup.blog/2020/11/20/miscellanea-my-thoughts-on-assassins-creed-valhalla/