I think the more pressing concern is why, in the US system, the government has the right to execute a person at all.
http://en.wikipedia.org/wiki/Capital_punishment#Global_distr...
It seems like in some of these other systems, people are executed for non-violent crimes too.
I think that's what he's got a problem with
At the very least, when comparing life in prison to execution, do not forget the sheer cost to keep them in jail for life. It may seem inhumane to say that, but these people are hardly humane themselves. Plus, in being forced to board them, citizens are negatively impacted for the rest of the criminal's life.