As discussed in another thread recently, the CIA hired him first and they are willing to take anyone who appears trustworthy. Eg, they'll take someone like Snowden who is not well traveled or educated and apparently patriotic, over an expert linguist who has lived in foreign countries a number of years and may have conflicting loyalties.
Disclaimer: I don't know this for sure, just repeating one explanation given in another recent thread about this.
>Considering this guy hasn't done so indicates he's not scared of whatever bad guys are coming after him. Which means, either he's really stupid, or he has no reason to be afraid.
He's been working with ex-Constitutional lawyer Glenn Greenwald since January. He is very well advised, and I'm sure he'll lawyer up if he ever finds himself back in the US.