I agree. Manning was a soldier under arms and oath to defend comrades and country.
Manning acted as a traitor and caused untold
death and damage. A firing squad was the proper and fitting punishment, certainly not
jail and then a commuted sentence by the still commander and chief of our military.

I bore arms in a combat zone in the Army infantry in the 60's. Our platoon leader would have executed a traitor like Manning in the field without trial.