Yep, changing rules and introducing KYC is standard practice of majority of bounty campaigns as their goal is to send as less tokens as possible, and KYC is one of the best ways to eliminate bounty hunters, all under pretension of wanting to eliminate the scammers.
Can understand this.
However, there is no mention of anything in "General Rules" the project can change any rules or anything during the bounty just like other projects did so they can easily ask user KYC or reduce token. So basically, they broke their own bounty since there is no rules project can change.