While I'm fond of any form of flipping the NSA-backing US administration the bird, the Nobel Peace prize has not enough reputation to matter in this context. Al Gore got it for raising awareness of climate change. Obama got that for not being Bush. Even if Snowden gets it, it doesn't really matter.
Yasser Arafat & Yitzhak Rabin were awarded it, its not clear if they intended to create a peace, but they did not. Henry Kissinger and Le Duc Tho were awarded it. Henry Kissinger meanwhile embarked on a major bombing campaign and Le Duc Tho declined the honour.
They've made premature or outright bad calls before.