If dumpers can dump coins and tokens in a reasonable way it won't affect the value much , lose in value when dumping happens if a dumper dumps huge amount of the token at once , this is a wrong way to dump coins, this is why till date some devs put locks on their tokens ,some even release percent by percent on term basis just to avoid huge dump.
The best way to dump is not to dump in an instant or a whole at once
Bounty hunters and investors are in a hurry to claim their rewards and profit, but if the project is good and legit and has something great to offer to the community, the dev need not worry, true supporters and investors will come to buy the dump and create demand on their token, the dev just need to continue working on their project.