Bounty hunters hate KYC because they can't join multiple account in one campaign because through KYC all bounty activity can be monitored and can only use 1 account.
As a bounty hunter myself I'm favor KYC so it would be fair to all bounty hunter that only 1 account to be used.
i think there is another reason for this dude.maybe they prefer to keep secret their identity document.moreover if bounty reward has less value.they consider it worthless if give their document.