Bitcoin should be forked and Satoshi's 1 million Bitcoin destroyed completely, if he really owns that much.
A sudden withdrawal of of 1 million (or large gradual withdrawals) should be regarded as an attack on Bitcoin.
Or it should be frozen for now until developers are sure no one is going to withdraw the whole thing and crash the market.
We don't know exactly who satoshi is, we don't know every of his addresses and how much bitcoin he holds. We also don't know the miner said to have 1 million bitcoin is really satoshi. And I don't believe we can just fork to destroy that coins without going back in the past i.e. about the time of bitcoin origin.