Maybe because Russia realized that Edward Snowden had a powerful name and they'd win favour with the lefties of the world if they protected him? That's one possibility. Or maybe because "let me try and be friends with the (perceived) enemies of my enemies." (although Snowden wouldn't characterize himself as an enemy of the US).
The important point is - a good thing done for bad reasons, might still be better than a bad thing.
The important point is - a good thing done for bad reasons, might still be better than a bad thing.