You have a good idea but it is still useless imo. Because there are many bounty participants who has an army of alts that can vote. Unless we sign-up for KYC first before joining the bounty to filter those alts.
That again is a horrible idea.It definitely doesn't fix the problems OP mentioned but makes the bounty process over complicated.Bounty manager or the ICO is not a legit entity to be trusted with someone's confidential information.That would just make participants go away.