I think when the price will drop down Mt Gox wont sell anymore because he will be in loss as well. Or he has got so much power that he might just rebuy at the lower prices and again start the compounding investment. This way he can keep multiplying his wealth and might be responsible for increased prices again.
Would be the most probable prediction on how bitcoin price would be and might he be the manipulator of why the price drop and rise. But in any case he would not sell all his holdings because he will still want profit from it in the future.
I don't think he is in it for the profit since he does not actually own the bitcoins he is holding. They are just selling them for purposes of liquidating the assets of Mt.Gox and not really trading for profit. This is just to pay off the debts of the company when it declared bankruptcy. Then they will just distribute what they got from the sale. I am guessing they have everything in record and no single penny will go to the guy who is liquidating it.
You are correct in that he isn’t in it for the profit, but if this trustee had any ounce of moral decency in him, he would still sell at the highest point possible rather than letting the assets he is accountable for generate a lot less in terms of dollar amount. The trustee team behind Mt. Gox have a decent bit of work to do moving forward.
We cannot know his rational for selling on the open market instead of a private sale or auction but there has to be some reason. He is being paid a substantial amount (I think about $3m) but it is not in bitcoin and is not dependent on how much he sells the coins for.