Not just defective; dangerous. And before you roll your eyes, consider that among the inmates of Supermax prisons are founders of the Aryan Brotherhood and other racially-obsessed prison gangs. Several of these men ordered or committed murders DURING their incarceration in general population, and managed to run criminal organizations that reached outside of where they resided. We're not talking about people who possess intelligence we desperately need; we're talking about men are determined to possess criminal power in the face of a lifetime of imprisonment.
Men like these pose a special challenge to our justice system. Yes, it's somewhat inhumane to keep them locked away from their fellow prisoners, but how should the state react when their actions prove they'd like nothing better than to indoctrinate prisoners of their own race/religion and kill outsiders? (Preach tolerance and love? If they're already in prison for life, what would their motivation be to listen?) It seems like some of them need to be isolated--if not permanently, than at intervals--both for their own protection and the safety of those around them. And, by extension, for our safety as well.
I'm not saying I'm not on your side; I'm just saying the issue is more complicated than being less liberal than one pundit.