The thing is it's NOT old coins. None of the old chaps is selling right now.
Just because the coins moved recently, it does not mean that they were bought recently.
Some owners of old cheap coins must have moved them to an exchange at some point, but withdrew them when MtGOX started failing, and people realized that exchanges were not safe places to keep your one's hoard.
Other old owners may have moved their coins to new addresses for safety or other reasons.
If someone pays a small amount out of a large input, and sends the change-back to a different address, the age of those the change-back coins will be reset for the purposes of the change-back formula, correct? What if the change-back is sent to the same address?
Finally, it seems that there is a lot of "fake" volume on the blockchain (coins moving between addresses belonging to the same person), perhaps from tumbling or hotwallet/coldwallet flow. For that reason, if someone sells a thousand 2011 coins, thus destroying a million bitcoin-days, he will barely make a blip on the chart (which oscillates between 2 million and 15 million BTC-days destroyed per day). If old owners have been selling a couple thousand old coins every day, we would not see it there.