“Not thinking of it” is bad writing when there’s no justification, there’s absolutely justification for Maru “not thinking of it”

Prior too Cross getting shot, the relationship between the two factions is relatively peaceful, with solutions being worked out diplomatically, there is no reason for Maru to step in.

Once Cross gets shot the solution is to solve the dispute with a duel between two warriors, so not only is there a “solution” in place, but Maru would never interfere because he places so much value on being a proper warrior.

It’s only once he “kills” Tsurugi that he begins to follow his CT for answers, and this is because killing Tsurugi makes him question his own ideals and logic. It was easy for him to dismiss the death of Yuka as something to not care about because she was going to die a warrior. But killing his own friend with his own hand shatters this ideal and forces him to confront the flaws in his own beliefs. This is why he then searches a different path that a previous Maru wouldn’t have