  In [8] Gerhardt proves longtime existence for the inverse mean curvature flow
in globally hyperbolic Lorentzian manifolds with compact Cauchy hypersurface,
which satisfy three main structural assumptions: a strong volume decay
condition, a mean curvature barrier condition and the timelike convergence
condition. Furthermore, it is shown in [8] that the leaves of the inverse mean
curvature flow provide a foliation of the future of the initial hypersurface.
  We show that this result persists, if we generalize the setting by leaving
the mean curvature barrier assumption out. For initial hypersurfaces with
sufficiently large mean curvature we can weaken the timelike convergence
condition to a physically relevant energy condition.
