Just curious, how can you be confident this was a hack?  I mean what is the probability that they've just had bad luck and never got a winning answer but have genuinely been playing fairly? 

Reason I ask is if it was bad luck you're inadvertently screwing over a genuine miner to subsidize others. (Although is surprising someone would leave that much BTC in an online account!)

I'm guessing you're very sure about this but would like to know how you're so sure.