Well, that's pretty nice of him to return a part of the money he has stolen. If it were me, I would kept it: what is the point to stole money and then give it back?
Obviously you have not read any post in this thread,maybe to try read post number 6?
There are at least two types of hackers,those who hack something or someone with the intent to steal something and others who hack some site/institution just to point to security flaws,but generally do not try to steal anything or do some sort of damage.In some cases, they are rewarded for their "work" becuse some company would lose a large amount of money and reputation if some bad hackers discover security flaw in system.
In this particular case I gave my opinion,it is possible that the hacker will return the rest of the tokens or he will keep them as reward for his work.