As others have already written, no one knows what's going on in his head - but what we do know is that he wants as much BTC under his control as possible, and like any businessman, he wants to profit from it to the maximum. How his actions today will affect BTC in the future is hard to say, but I personally do not think that it is positive for all of us that one company owns so much BTC.
However, in a market that is completely open, anyone with money can buy as much BTC as they want, now it's just a question of how much someone thinks is enough. I can't imagine having that much BTC for the simple reason that even 1% of that amount would be more than enough for me - and on the other hand, BTC should be a currency, not just an investment that you make indefinitely.