Does this mean he got was able to withdraw and keep 5 btc on account of the exploit?
Yes. He had used the exploit to get somewhere in the order of over 30 BTC in profit. He did withdraw his original deposit, plus 5 BTC as a bounty for finding the exploit. Had he wanted, he would have been allowed to withdraw up to 25 BTC which was the contents of the hot wallet. But being a decent guy he didn't even make an attempt to do so, something that I am very grateful for.