The president is empowered to protect and defend...
Enemies at war with the U.S., their allies and U.S. Citizens enabling the enemies are not subject to Constitutional guarantees. None!
They are subject to a firing squad.
I hope you'd be ok with John Kerry deciding what "collaborators" should be subject to the firing squad. What if decided that you were in league with AQ. Under his inherent authority he'd be allowed to shoot you. Who could stop him, he has inherent/plenary power.