Imagine that cyberwar really is a new kind of warfare that is about to emerge. This may or may not be a useful way of viewing the situation, but governments do seem willing to attack each others' infrastructure, causing great damage to civilians in the process. They have also begun using the kind of surveillance that is usually only justifiable during wartime.
If the Internet is being militarized, Snowden has pointed that out. He's shown that the NSA is actually one of the "standing armies" that the Peace Prize rules mention. Now we can talk about reducing it.
I still think it would be a stretch to award him the Peace Prize, but anything that keeps the Internet from becoming a war zone promotes world peace.