The world is recognizing that he is an anomaly, that he simply SHOULDN'T exist.
He basically smashed fate into pieces, the list of his crimes reaches to the sun and back to the planet.
is it necessary to kill her though, it's not like her power is necessary for the current Amon right now, I think it's just the author's sadistic tendencies kicking in. I might be biased here since I liked Shirahosi so watching her die like this quite irks me.
