It's a bit of tricky question, everybody will shout "ban them!!!" but if do this and the campaign ends up with 20-30 users, will the guys from cryptotalk/yobit keep you as a manager? They are probably far more interested in the number of banner views than merits.
Makes sense no doubt Yahoo is a good manager and he wants a well manage a campaign, because this is the one that sets him apart from the other managers, but in the end, it's always on the goal of the project and the developer, excellent posters make the forum better but not the project who wants views and visibility.
Also if you checked Yobit campaign history anyone and anybody can get in as long as he is a senior or hero or legendary rank, they never restrict the numbers.