i think that is a very bad habit and it is worth giving such people native trust in such act, it may warrant you loosing your work or having native trust.
but to me what you will do, try to pm the dev or report on the bitcointalk thread so that the manager can also see that and handle it.
indeed, any act that cheats the bounty campaigns will end into earning negative trusts. the worse is - your account will be banned on joining any bounty campaigns if your account is listed on other admin lists.
Some bounty managers are checking their participant's reputation all over this forum.