Accelerator wasn't inherently evil though, he was practically cultivated to be a killing machine for the sake of Level 6. Like yeah what he did was absolutely horrible and fucked up, but that's kinda what happens when you make a child kill more than 10,000 people that were actively attempting to harm him.

I did always like the twist of fate where his life is now dependent on his former to-be victims. I had no qualms with his redemption arc.