As per the statistics "Satoshi Nakamoto" mined around 1 million bitcoins in the early stages. So, he has gotten the same quantity of BCH as well.
What will happen if someday he might see his project at risk of overtaken by Bitcoin Cash. Could he be dump his BCH stake anytime?
What makes you think Bitcoin Cash is not "his project", but Bitcoin is? In any case, I don't see him dumping any of his coins or moving them, as they could give clues to his identity. Only if he really needs the money, will he do so.