If you think good and evil as a classification with only two classes of "good" and "evil",
it becomes a most rough classification
(if it has only one class, you do not call it as "a classification"),
so that you can classify easily anything or anybody to whichever as you like.
If you classify your enemy to "evil", no matter how many millions of enemies you killed,
you may have an illusion of that "I only destroyed evil."
In other words, the Rounds tried to form the delusion below for their self-justification
instead of the illusion of "The Triangles are inferior" that was already destroyed.