the context he's missing has to do with the sofa that maliki wouldn't sign. america is now in the region on the invitation of the iraqi state. that's what all this is angling for, and what the long term strategy is: a permanent troop presence. they just need the iraqis to sign the right papers; papers maliki refused to sign.
honestly? i'd have a hard time giving them immunity after some of the reports coming out. i really think american soldiers ought to be accountable under iraqi law.
but, when you're the empire you get to break the rules.