There is nothing bad in satoshi holding a million of the total supply of bitcoin. Thats like 1% of the supply.
It's actually around 4.76%. Sorry. Couldn't help it. 
How is withdrawing 1 million BTC an "attack" on bitcoin? It's Satoshi's money. Let him do whatever he wants with his money. He can spend it all on blackjack and hookers and hell do I care how he wants to spend it.
Right, let him sleep in peace. Don't disturb him to say 'freeze his/her 1 Millions Bitcoin until he is active', it is Satoshi's money and he will decide when he will withdraw his money from the market. The last 10 years he is holding from an unknown source.