1 Million is a fair share and this share alone makes Bitcoin significantly decentralized because it's in good hands but if Satoshi doesn't ever appear, then this shair means nothing.
Quite contrary, if Satoshi (remember it could be a group of people represented by 1 guy) was to move his coins, it would create panic in share holders.
Satoshi could control the price of all Bitcoins by pumping and dumping.
The best case scenario for Bitcoin is for this coins to never move.