Let me share my opinion. Lancer was marked "AOS" on screens for a valid reason, and leaving in that situation could lead to a ban. However, a later message stating that Lancer was no longer marked "AOS" complicated the situation. If Lancer left after seeing this message, it's reasonable to assume that he thought he wasn't marked anymore. While Lancer's actions did violate the rules initially, it wouldn't make sense to cancel the "AOS" later if it was legitimately given. Nevertheless, confusion could arise from the subsequent message. Therefore, I believe it would be unjust to impose a ban in this case, even if Lancer wasn't entirely faultless.
