To my understanding, KYC simply means "Know your customer". Investors(customers) who participate in ICO are made to go through KYC process before they are even allowed to purchase their tokens. On the other hand, Bounty hunters are just "part time workers" of the project and not customers. Even if they will be made to go through a KYC process, it should be before they start working and not after. Waiting for them to finish working for the project and refusing to pay them because they failed to pass KYC afterwards is a total cheat.
KYC I think is depend on the bounty manager, and there are some project that from the bounty thread they already announce already that KYC is required. Now its up to the participants if they want to continue to apply in that campaign. But in some instances there is truth sometimes that kyc was just to cheat bounty, of course if the participants will become reject or declined for it, where do you think will go the allocation token for that participants?