According to your logic, wouldn't that be a waste of 12 taxpayer financed bullets?
No it's not a waste of taxpayer money when you are getting rid of a piece of shit terrorist scum. Plus it's a hell of alot cheaper.
There is little doubt he will be found guilty by a court martial and will hang. Mig, certainly someone of your intelligence knows that what makes this country great is rule of law, and what brings it down is the absence of rule of law (See, e.g. Bush-Cheney).