I have to say, I've never understood this argument. I would regard the loss of my freedom as being as bad as the loss of my life.
So if you were convicted (we'll assume wrongly convicted) of a serious crime and your lawyer wanted to push for imprisonment instead of death you'd say "don't bother, it's all much the same to me"? I think most people value their lives rather more highly than that.
Andf loss of freedom for what period of time? You think that 30 years lost freedom is as bad as death, how about 10 years? 5 years? 1 year? If all those are as good and bad as being killed then are they also the same as each other? Does this only apply once you get into a term of years or is half an hour being detained for questioning as bad as being killed too?