Isn't it the job of the bounty manager to check the validity of the entries ? Why not just run the bounty campaign yourself then, as you're doing most of the heavy lifting.
Let me give you my personal opinion. Managing bounty campaigns and checking alts/bounty cheaters are two different jobs, and both are difficult. Campaign managers are required to have organizational skills, manage the running of the campaign, communicate with clients, arrange payments, validate eligible posts, and so on. Some campaign managers may not have time to double-check their participants, or there are some things they missed. So this service makes a lot of sense to me. This does not mean that this service will be 100% able to clear the bounty. But this is like installing additional safeguards to control the quality of the bounty according to the campaign manager's standards.