(( Is it honor? Or is it a personal vendetta against all those things that would make human lives harder? Of course, he understands humans are pretty damn good at doing that, too, but he'll prevent those small evils from happening that he can. ))

My understanding, which is not at all nuanced, is that theirs is a pantheon that strives for balance... I suppose in that light it could make more sense that they're all fulfilling their assigned roles: Set's being chaos and destruction.