The problem for the author is that he opposes the death penalty. Rather than re-evaluate his principles to make room for even extreme cases, he chooses to corrupt the uncorruptable.
The problem for the author is that he thinks that it's a real social issue. Like the "ticking time bomb" and the trolley problem, such simple problems do not exist in real life. There are no serially-escaping supervillains or uncorruptible invincible heroes out there - and life in prison is a way to guarantee that a garden variety villain can do no more harm.