He is listed with another person under co-design, but not on equal footing with Alex Cutler.
The game may provide no financial benefit to Matt Fantastic, or any benefit to him may have been upfront and not tied to sales. Board gaming companies do not have large profit margins. It is quite possible that the co-design credit was all he got.
Alex is the only one listed under design, and the only name on the front of the box. He and the publisher are the ones really taking the hits, not the man accused of attacking anyone. That's a lot of guilt by association and collateral damage.