Russia doesn't give a shit about Snowden, of course, but Putin cares a lot about his own image of power. Such event would be a huge slap in the face for both the country and him personally - it would make Russia look weak and that's of great importance for their internal politics and Putin's ability to keep the public support and stay in power. So it wouldn't go unpunished, you can bet on that, he would be forced to demonstrate the power somehow... not for Snowden, but because of his voters...