Honestly, the best way to modify the reviews is to install some form of human moderation instead of having all these weird, overly complex requirements (why shouldn't new accounts be allowed to give reviews? That makes no sense). It's the content of the review that matters, not the status, levels, age or whatever of the various accounts.
Spam reviews? Deleted by moderator. Abusive and insulting reviews? Deleted by moderator. Harassment? Deleted by moderator. Bots? Blocked by moderator. Critical but fair reviews? Approved by moderator (edited if necessary, if the dude was swearing and insulting).
Moderators solve everything. Unfortunately, it's apparently not feasible because you need a dedicated team of moderators to go through thousands of stories and reviews everyday...