I cant be so sure about who is right and who is wrong from just few screenshots, but if the bounty manager is claiming that the bounty is scam, ask him to put proves before commenting.
If he can prove that it was a scam project, then nothing could be done. On the other hand, as your screenshot says that the bounty manager is denying to update the spreadsheet, and asking for only his payment and leaving the bounty hunters behind, if that is legit then you can leave negative trust to his account so that in future more people could be aware about his task/ask.
Personally, I have never seen this bounty manager before