Sure he can!
It's a busy time right now! Right? RIGHT?
And even so, it's simple enough to say "No.", couched in suitably political terms.
You know what I'm talking about.
At this time *EVIL RUSSIA! EVIL RUSSIA!* we don't have enough information *EVIL RUSSIA! EVIL RUSSIA!* on the situation to make us comfortable pardoning him for stealing secrets and giving them to EVIL RUSSIA!
Basically, what would have happened to him, had he come home is he would have become Bradley/Chelsea Manning Mark 2.
He'd have been dumped in a prison. Rotted for a while. Then announced that he'd decided to cut his dick off and live as a woman. Turning him into a complete laughingstock meme and totally detracting from what actually happened.
I think Snowden likes his cock and balls right where they are...