Why not?
It is possible as it is part of their business, so if they keep their promise, pay to review campaign participants fairly by themselves or by review campaign manager (outsource), it's helpful for their reputation.
It's one of ways of gaining reputation but there are more important contributors for their reputation: platform operations: deposit, withdraw, provably fairness and more.
I think running a review campaign can be a valid strategy to gain exposure and build a reputation but it’s not enough on its own to earn long-term trust. A trustworthy casino should back that up with consistent transparent operations especially fair payouts and others that have mention above without these no amount of positive reviews will hold weight. Reputation is earned through action not just marketing.
I also support the review campaign, At least this will put many doubts to rest, at least the manager has paid all the campaign participants and Betkin is venting on continuing with their forum presence with the review campaign launched a few hours ago, this shows that at least few forum members will have a chance of checking the site out and giving their honest reviews.
So let's hope everything goes well with this casino and they can build a positive presence here we await to read other forum members' reviews about this casino.