It's funny, because I'm actually anti-death penalty, find a lot of what Jason does to be distasteful and ultimately damaging, and think the character himself is completely nuts, but at the same time, I love him so very much as a character, find him incredibly sympathetic, and certainly don't think he's evil, or even a bad person- just confused and misguided.
Of course, as you said, the DCU is a whole different kettle of fish, where prisons are made of paper and the like, so I guess, in that world, I might find his actions a lot more justifiable anyways, even if I don't think he's stable enough to be the person making that call- I mean, if someone like the Joker proved so very, very deadly and generally uncontainable? Yeah, I'd be in full support of offing him. I don't like the death penalty, but sometimes, for the good of the public, the mad dog needs to be put down.