He'll eventually have to do something with his coins, unless he wants us only to have 20million coins instead of 21.
How do you guys believe he will go about getting them back into the bitcoin economy? Multiple wallets or not he mined a good sum of blocks, and the coins still remain at the coinbase address.
Let's hope those coins are lost forever. The fear of them possibly flooding the market would make the price fall hard. Not that it would change how bitcoins work but it would be a problem.