I don't think that bounties are generally enforceable. In an informal bounty like this without specific language to the contrary, the bounty creator retains sole control over who receives the bounty, even if the community disagrees with him. So I don't think that xDeathwing is obligated to pay anything, though due to the confusion and small amount of money involved, he probably should pay 0.5.

I removed him as a moderator because this is all a bit shady, and his conduct in this thread leads me to believe that he is too reckless/careless to be a good moderator, not because I believe him to be guilty of scamming in this case.