So this was most likely planned out to coincide with the payout?
Without doubt. I'm surprised they didn't squeeze another 20 hours of mining profits

I guess once you are over $50m it's all the same...
That's a common misconception, but a few million here, a few million there, pretty soon you're talking about real money.

This is why use the jaws of life to get the last bit of toothpaste out of the tube.
There was an attack on bcc that hurt the scrypt profit-switching pools just a day before this. I'm really not sure this heist was all about the money, or at least, not just this particular pile of money. The perps may be playing a much bigger game.