"How could AG Eric Holder justify refusing to authorize the death penalty process for Boston Marathon bomber"

I'm against the death penalty but not a big fan of the term "abolitionist," though perhaps given its anti-slavery origins, that is misguided. It seems more that the term is too often used to imply "extremist." Anyway, a blog (who supports it for extreme cases) asks that question, I assume not including "it is never appropriate." I tried. Toss in no deterrent value -- a crime like that, execution adds trivial deterrence especially given his age and cause.