Why do you overcomplicate everything? A bug that leads to missing out on $160k+ revenue is an expensive bug.
Splitting hairs here, but since I live in the IT world it was not a *bug* it was *bad programming*.
It did exactly what they told it to do. What it did was wrong in terms of being a valid block.
As for the $160k price tag, it's a tough call. If they had made the block properly would they have found the block or would that miner who got the work from the server gotten it 1/10th of a second later so the randomness of mining would mean that it did not find it.
-Dave