It's far more credible that Snowden is the US's way of announcing the all-pervasive surveillance dragnet that's been in place since the internet ever existed. So, altruist? No.
Although everything is possible, I'm not so sure about that, simply because it involves a whole lot of complex dependencies and there would have been an easier way to make this announcement (for example via wikileaks). Especially the motive behind making such an announcement voluntarily remains unclear.
Well, Snowden's version of events is not plausible, so reading between the lines is necessary if you're interested in the truth.
I think the point of Snowden (and the reason why a simpler route of using Wikileaks didn't occur) is as a Plato's Cave styled rhetorical narrative. The idea would be to introduce (with huge drama and journalistic attention, just so everyone hears about it) to the wider public to a new archetype: digital rights hero/villain, hence simultaneously fostering both hero and villain narratives, depending on which side of personal freedom one's politics resides in (another establishment classic, divide and conquer dialectic). This would help to ensure that the possibility of real whistleblowers with less politically convenient ideas about the surveillance culture never step forward "because someone else is doing it". It's a public relations classic: bad stories should be front-runned and controlled as much as possible by their subject, "get out in front of a bad story" is the short hand.
And that sort of perception management should concern every single Bitcoin user out there: you are a future target of where this new cultural phenomenon is going to be pushed to. The public are being trained to condemn future Snowden-types, where before they had little to no opinion, or considered nerdy types as non-threats. Information and it's perception are becoming highly sophisticated weapons of totalitarianism,