Yep, this is a good one.
I would add: what if the original owner has died (or just thinking about death and inheritance) and now his money got split between members of his family?
Hmm, not so sure, it doesn't look like or feel like it.
He is spending full inputs and moving them into batches of ~90
BTC but not of equal value, there is a 5
BTC difference between the current 5 addresses that hold those coins, plus he would have moved them all, right? If it were an inheritance they would have done it with all of it combined, not leaving some there, and for sure not a 3-hour difference between the two outgoing tx.
Well, probably I'm inclined to think of this because that's what I would do if I were him, split it slowly and carefully into small batches, make the back-ups, split again, and then slowly erase the traces by mixing them before liquidating smaller amounts. With $40 million even if I would go through KYC and pay all my taxes and be completely legit I still wouldn't want anyone to trace my steps. Imagine making a one-time payment at a coffee shop in the neighborhood or some online store with your name and address and some employee with too much time on his hand discovering you have 1000 BTC on you!