Troels,
as an organizer and manager of the Sputnik bounty project you don't need to advocate or defend your decision here or anywhere else. The right to make the decision was fully yours as it was you who put the energy and reputation into the project. You don't need to explain the details of your decision to anybody. Do NOT let anyone tell you something different or make you feel guilty!
In my opinion your decision was right and logical result of several deadline breaches and lack of communication from the bounty hunter. Cancellation of the bounty was a rational decision and every good manager would do the same (if not sooner).
Good luck with future bounties.
