I can see about 3-4 camps in the thread:
Those who want him killed, now: When people talk of injuring-killing Loughner for what he did they are talking about revenge, there have been more than one or two posts by those who would be judge, jury and summary executioner in here, that is about revenge/anger/getting even, not "repercussions" or what is best for society or any other noble cause. Just wanting to hurt him.
Those who seek the death penalty: Those who are talking about the death penalty needing to be on the table are not being so emotionally rash about things but if he is found to be not mentally culpable and they still wish to see him executed then I would question their motivation.
Those who don't seek the death penalty: Unless the issue is sanity, those who object to the death penalty would generally do so regardless of the crime.
And of course, those who are attempting to point out that the first category of people are about vengeance not justice.