Frankly, I agree with Jag that "confirmed" is kind of a strong word. He may or may not be INTP. It's my instinct that he is, but absent the man's actual input all we've got is speculation. Most of us wish we had the courage of our convictions, and there's the desire to see that possibility reflected in the actions of another we deem to be "like us".
I came across this quote from Putin on Snowden a little bit earlier, and it pretty well sums up some of my own feelings about the whole affair:
Originally Posted by Vladimir Putin
"You know, I sometimes thought about him, he is a strange guy. How is he going to build his life? In effect, he condemned himself to a rather difficult life. I do not have the faintest idea about what he will do next.
Putin said while US special services consider Snowden a traitor "he is someone with a completely different frame of mind and considers himself to be a fighter for human rights."
I thought INTPs had all the vision without the motivation, whereas ISTPs were calculated risk takers. This was a huge risk. Are you sure you would have managed to get off the couch and see it through?
According to Ars Technica, the CIA/NSA were, just as Snowden was stealing the documents, starting a program where they would investigate thousands of their employees to see if they might be spies, and analyzing the records of accessed documents. Thus, this situation can be perceived of as an emergency - Snowden had access, and if he didn't act soon the opportunity would be lost. Instead of panicking, he pulled it off with calm, cool, collected grace. Instead of doing nothing, he did everything.
Despite the confirmation bias involved, I continue to bet ISTP.