Sometimes, you are about to die, and do not onow anybody in particular deserving to get the big present from you. So you take it with you.
If you do not tell the world about it, the absense of your part in this worlds financial system will keep the prices artificially inflated for a while. If you tell by sending it to Satoshi, the impact will be much faster and perhaps the prices will be more fear sooner.
Or it is just Satoshi himself consolidating his savings.
