This is one of the inevitable illogicalities of the boost nomination programme. The owners of specialist niche publications are chosen for their experience and expertise in that field, to select the finest stories. But the decision then lies with a curator who then, by definition, is less of an expert than the person whose decision they are supervising.
One could argue that the curator is the skilled representative of the lay readers, adjudging general-interest criteria and deciding whether non-experts would also be engaged.
But there is at the least logical awkwardness to the structure.
And if the role is instead above all to maintain Medium's corporate standards, then it would indeed seem that in this case they may have failed.