Bounty manager is just doing his/her job, I do not think him/her should be blamed however after proving the confirmed scam, a good bounty manager should close the campaign. Also the participants should do the same, leave the campaign.

A good example: yahoo62278 closed the ARBITAO Signature & Avatar Campaign.

That's an example of integrity right there, which I highly doubt most of these altcoin bounty managers have enough of in order for them to do the same thing if this situation presented itself in a bounty they managed.  aTriz was very trusted as a campaign manager right up until the point where he went along with the scam his campaign project was trying to pull off.

So yeah, it all depends on what the bounty manager does once the information about the scam becomes known.  The same thing holds for the bounty participants.  If the project is known to be a scam and they continue to advertise for it (assuming the manager hasn't pulled the plug), they'll probably get negged.