The cynic in me likes this interpretation, but "the documents" aren't capture-able any longer because they're not all in one place. Several people have access to them, some of whom are not stupid (Bruce Schneier, etc.) and can operate redundant distributed cryptosystems. The cat is out of the bag on this one and it's never going back in. This doesn't stop them from wanting to arrest/torture/kill/* Snowden, but the government isn't dumb enough to imagine they'll ever get their papers back.