I was expecting to read about project development when I read the title and not a bounty related concern.
Anyway, the best thing for you to do is make your case in the Reputation or Scam accusation board. Do you have enough proof that they have ignored the hunters? Nobody can actually solve the problem other than the bounty hunters themselves. Do not expect anyone or the forum to do things for you.
Make a good case as I said already and/or create a flag against these projects you mentioned. Do you know how to do that?
agree, projects like that should be reported whether they are scam or just ignore like stalling time etc, because those who can get evidence of the incident are those who have promoted the project to the end, so they know something that is indeed a fault of the developer to harm all who have worked for him to the end