Humans are more monsters than demons most of the time. I'd believe him.Nothing says "for the sake of humanity" quite like massacring humans.
Nah, it's probably just their country, while they themselves have delusions seeing others fall to demons, having a urge to unite everyone under themselves as to "protect them". Because the surprised look back at their own troops ruining a "honorable" test of strength seems like the main foreshadowing eventCalling it right now: this dude is being mind controlled or manipulated by the demons.
Schrödinger's Hopes and DreamsIn b4 "The emperor ends up being another woman added to Sieg's harem"