The problem is not just bounty hunters, I think bounty managers should warn project teams of what could happen.
There are various mechanisms to solve this problem:
1/ Distribute the tokens/coins in several phases (with the consequent anger of the bounty hunters and their FUD).
2/ Pay the reward in popular tokens/coins (BTC, ETH...).
3/ Do a buyback program with some incentives.
I'm sure there are more ways to avoid a dump and thus avoid problems, as soon as I can I will expand this post.