Saying it doesn't fit to any category and excluding it as such would be enough. The rest of the review is in that case unnecessary. If no category is available, he should say so.
Utopian cannot afford a moderator for every topic...
I will not tell you what to do or how, but I personally find that the 25 submission priced 6.5 sbd upvote per week is a bit of an overpay for a single reviewer. You can pay more people under affordable sum.
Thank you for the clarification, it is enough.