very stupid of them to give hackers the BTC. Giving a thief more money and hoping he will return when he has no obligation to do so.
They got 5M back, that's worth >300 btc. Bter won in that trade.
They traded only 10 BTC for the 5m NXT though. The hacker said the deal was off but they foolishly sent another 90 BTC to his address.