Simpson1 has recently reported evidence for a heavy neutrino of ~ 17.1 keV mass. Cosmological bounds on stable neutrino species imply that this neutrino (vH) must be unstable. The most likely decay mode, vH --> vLf where vL is a light neutrino and f is a scalar boson, leads to the cosmological scenario presented here, which is quite different from the conventional one. In this scenario, the Universe becomes matter, dominated at a redshift of z~107 and becomes radiation-dominated (by the decay product vL of vH) at z~310. The kinematic constraints on the lifetime of vH do not lead to any contradictions. On the other hand, the growth of baryonic perturbations is severely limited in this model because virtually no growth can take place in the radiation-dominated region z<310 and decay of vH is likely to disrupt and smooth-out past growth by a large factor. It is doubtful whether there is a simple way to avoid this difficulty.