Yeah, but in context it's the hypothesis that sterile neutrinos explain the anomaly. I edited the post above after checking the research article.

They also say, > we reject with high CL the hypothesis of a sterile neutrino of mass around 1 eV.

Viable sterile neutrino dark matter models are generally at least 1000 times heavier than that, in the keV range. That's because if the dark matter particle were too light, its thermal motion would eliminate variations in the density of the universe at the scales of dwarf galaxies, preventing those galaxies (which we observe and hence know to exist) from forming.