Price dumping is no longer new, is something we all can't control and talking about bounty, projects doing bounty are doing it mainly to create more awareness about their project throughout the world with the hope of gaining more support of all cryptocurrency enthusiasts, so I don't think bounty has anything to do with price dumping.
Those who have a lot of tokens (one of them bounty hunters) have little effect on dump prices when they sell all tokens. But the most influential are investors with large financial capital.