Manning released much more information then regards that single incident. He released information regarding informants, troop strength, troop movements. He endangered quite a few people.
Printable View
If they are going to execute him, its most likely going to occur only after/if he is convicted and then only after all his appeals are exhausted.
Contrary to your wishes, I believe that either he'll receive the lethal injection, hanging or firing squad. either way it'll be over rather quickly for him.