The NSA is whatever the NSA wants to be, apparently. "Spying on foreign leaders" seems to fall under what the CIA does (or apparently did, Pre-drone), so that is where I feel the distinction lies.
Perhaps I could see your point if Germany was also busy appropriating Poland or France. But, sure, maybe in this case, they were doing what we created them to do. Oh, wait, 'we' never got any input in that process.
This is a complex issue. I agree with evildictaitor in that what he has done is beyond reprehensible, you don't sign up for a sensitive job and then be as indiscreet as he has been, what he has done is wrong and unacceptable.
There is a little of the common philosophical question in this, in that elementary philosophy question that asks whether a man that steals to feed his starving family is committing a crime?
I think he has made more than his point, and wish the US government could find a way to bring him back to America or to send him somewhere where he is not continually feeding people information that will destabilise the West, because everything that is coming out now is extremely damaging.