The authors address this this to some degree in the Discussion. See the para beginning "Indeed, naked mole-rat mortality was less consistent with a typical Gomp

The authors address this this to some degree in the Discussion. See the para beginning "Indeed, naked mole-rat mortality was less consistent with a typical Gompertz model of hazard than it was with an exponential decay model, with a constant probability of decay (death) defining a species’ half-life."