He may be the largest holder for now, but that does not change anything about what bitcoin stand to offer, if he decides to withdraw all his Bitcoin, does that means he's going out of the market completely or he just want to use the strategy of buying the dip and hold, besides, I don't see any relevance in knowing about what Satoshi might do or how the market reacts towards his decision to withdraw or sell all his Bitcoin.
With his massive Bitcoin fortune that if he cashes out, he won't be able to use all of such huge money, I think he does not mind of selling and waiting for opportunities to buy back, buy dips later.
In addition, person like Satoshi Nakamoto can have Bitcoin addresses that we can not know as all estimations on his bitcoin holding used an assumption that early Bitcoin addresses belong to Satoshi Nakamoto. While in reality, he would have mined bitcoin a long time later and would have used addresses that are not in any assumption.