Well, I’m not arguing the semantics of the words “tragedy” and “redemption.” We know what I’m saying. Ben’s turn to the dark was lamentable, and I believe he should have the chance to turn back to the light.
Whereas Ben and (a handful of students with him) killed only the remaining students (less than a dozen) after his teacher tried to murder him.
Unless we are believing Luke is lying, Ben had already turned to Snoke by the time they had their fateful moment in the hut.