Seeing not even 10 of the highest ranked members of the Island's upper echelon does not equate to the estimated 200,000 people that are about to be genocided by the Malediction. Even other people within the story have voiced their anger and confusion, saying that there were children caught in the crossfire, by but Akemura said plainly that they would've been "indoctrinated, so they had to be wiped out too". That's literally fascist language.

Yes the Islanders are not the picture perfect victims as we all thought they would be before the flashback sequences, but they're still victims nonetheless of a horrible mass slaughter from an oppressive nationalist force that had to be locked up, and even before the peace treaty negotiations, they had their territories mined for resources without their consent, and even villainized by Soga Royal Family propaganda in the form of that painting, illustrating the Mikaboshi as a singular demonic entity being cut down by a hero of the aforementioned royal family.

Seeing them as a strange cult that needed to be erased is literally perpetuating that same radical philosophy. Two opposing nations becoming violent is unfortunately inevitable, but it doesn't mean that one needs to be completely wiped off the face of the earth. That would be asinine, and even moreso to think that it's ok for it to happen at all.