Earlier quoted context omitted.
It's important to realize that common sense is never a replacement for a proof or emperical result. That is, common sense is not sufficient to refute the claims made by the original paper. The power of science is that it often defies reasoning and in so doing provides new insights into how things work.
But a clearly absurd or nonsensical result should be enough reason to double-check that the proof and results are actually valid. Common sense may have a somewhat low weight for evaluating how probable some scientific result is, but it doesn't have zero weight. And neither does the possibility of experimental error.
Lu Hong†‡§ and Scott E. Page¶ †Michigan Business School and ¶Complex Systems, University of Michigan, Ann Arbor, MI 48109-1234; and ‡Department of Finance, Loyola University, Chicago, IL 60611
Now that "Business school" part, that's a good reason to recheck the conclusions.
Heh, I'd like to pretend that a rebuttal to business school ideas will actually change them, but we all know how this will play out.
The idea of diversity is imposed from above, and no-one will care about this. Politics is the origin of the diversity idea, nothing else.