It is said he owns 1,000,000+ btc and he just lets it sit.
It is not very trustworthy for him to have done this deliberatively as he could case huge damage to the market with cashing out those coins.
In a way we are all at his mercy.
Dunno, somehow I think that if Satoshi really had some bad intentions, like amassing BTC and then dumping when price reach certain point, he would have done things differently, and definitely get more than 5% of the total supply. Him owning 5% of the total supply would be least of our concerns in that case. Anyway, I am not really afraid of that happening.
This is what guy that found those bitcoins think about chances of Satoshi dumping BTC
Patoshi Researcher: 'Satoshi won't use his coins ever’