His reason is that it would be more humane, which shows some historical ignorance: in particular of the Holocaust. The gas chambers were introduced as a more humane method of execution since the firing squad executions caused the soldiers to suffer pangs of conscience.
Of course, this method of execution didn't really have much of a deterrent effect as this resistance member demonstrates.
All in all, it sounds like a really bad idea and is getting a lot of play--mostly negative.
Although, I am sure there are enough blood thirsty people in the US willing to volunteer for this duty.