I agree that even if you considered the point of prison to be quarantine, it would still be a punishment. However, if your goal is quarantine rather than punishment, you don't need to choose the solution that maximizes suffering. I disagree that death is only acutely threatening if there is something after it. It depends very much on how highly you value your remaining lifespan. Right now, I'm enjoying life, and I'd be more disappointed about my reduced lifespan than afraid of the transition. This is actually pretty new to me; l I feel like I understand where you're coming from. Not sure what else to say about that. Feelings of solidarity and respect. It's not even clear to me that a life sentence in prison would necessarily be a net negative. I'm sure there would be some suffering, but hedonic adaptation would have your back, and I hear some people get to read a lot.