Indeed, i don't see any benefit from asking such questions while we already know the owner of those addresses and his goal to transfer them. There are many old dormant bitcoins stored in old generated addresses. Each time some of them moves we will try to get answers to those questions? This is somehow childish. Even if the owner decided to sell his fortune, the value of those 400$m worths nothing compared to the actual circulating volume in exchange markets.
You have enough time and expertise to track those bitcoins, go ahead. I am pretty sure that you will obtain nothing in return even if you can prove that they belong to Satoshi himself (almost impossible).