  The study of the decay of an accelerated proton recently provided a
theoretical proof of the Unruh effect. On the basis of general covariance of
Quantum Field Theory, indeed, it was found that the decay rates in the inertial
and comoving frames do coincide only when the thermal nature of the accelerated
vacuum is taken into account. Such an analysis was then extended to the case
with neutrino mixing. In this Letter, we show that, by further embedding
neutrino oscillations in the above framework, general covariance necessarily
entails the use of flavor neutrinos as asymptotic states, as well as the
occurrence of neutrino oscillations in the Unruh thermal bath.
