I think the way out is for the project to pay bounty hunters with Ethererum or bitcoin to keep their coin from not being dumped. Some projects use the same method and their coin survive and it is doing well in the market as we speak now. I can see how paying with Ether will harm their projects but it will protect them and their investors. I agree with you that the hunters attitude is bad and highly inimical to themselves. How i wish it can be controlled but how can you even tell somebody not to sell his token.
Project pay out in tokens because they really do not want to spend much to achieve the promotion of their project and bounty is an easy way to go. So, paying in other digital currency defeats that objective. I would say the best thing to do in such scenarios is to either lock the bounty participant’s token for a long time until the market has developed to some certain extent.
However, let us not forget that bounty participants always have just very little of the total amount at the end of it all, and I would not say bounty hunters are the major culprits of driving down the market value, but would rather state that, this is an act of whales to just drive out the weak hands out of the market at lower price.