Obama should prosecute Edward Snowden as an enemy of the state.
Snowden took an oath when he went to work for the NSA that the information to which he would be made privy would remain classified, but he broke that oath according to the dictates of his conscience. His was an act of disloyalty - criminal disloyalty.
If we have government workers who think it is acceptable to break their oath of secrecy and loyalty as their personal consciences dictate - an oath they explicitly affirmed and correlative obligations they willingly agreed to discharge when they chose to work for the government - and to exploit their security clearances, attendant upon which is an implicit oath to protect the information to which they have unique access, who's to say what might be revealed, and to whom?