Bounty is only profitable in bullish market, OP is correct, even if it's only 2% but when no one is buying and bounty hunters would like to dump their reward, they will likely get a very cheap price which is not good for the project as it's future will definitely be at risk.
Don't forget investors and developers, it's highly chances are they will be the ones who will sell coins first on the exchange.
That's why bounty hunting will no longer be feasible.
If the project wants to succeed, they should not release the bounty if it will cause a dump, they should delay or maybe distribute on a monthly basis divided like 12 months, it's actually helpful for both as bounty hunters would like to get good value but they are just force to sell even cheap when they have it.
The price is easy to shake in exchange, the whales will easily prepare their action, because there will be a "pattern price" on the exchange. Market sentiment will be easily shaken as well as the community.