The nice guy trope goes a hair too far in most mangas in my opinion, and makes that character boring. Writers of fantasy fulfillment stuff know that the vast majority of people simply want a reason, any reason, to justify themselves.
The way Yoke's character is written is increasingly like why classical Superman is boring. He's lawful good at all times and by definition has to be right because of it.
While the melodramatic presentation really isn't my cup of tea. Think about Simon:
Everyone wants to be the hero of their own story and for a while he gets to be the hero. Viscerally, in a way that none of us ever will in our own lifetimes... Except he gets to see that die because we... weren't nice?
Hell, if the manga were from Simon's point of view, all we'd know is Yoke selling his soul to a dark god, confirming Simon got screwed out of something he perceived he deserves, and this would shift to a revenge fantasy manga.
It's a bit trite if someone's trying to make a statement on morality.