  In this Letter we present strong arguments in favour of thoroughly revising
the negative mass cosmology (NMC), which has been proposed as a simple
alternative explanation of dark energy and dark matter effects, within the
framework of General Relativity. We show that there are various physical
predictions in this model which require fine-tuning in order to make them
compatible with current cosmological surveys. In this way, the original
motivation of the NMC model becomes obscured due to the imposition of
fine-tuned unknown variables. We conclude that a more rigorous theoretical
treatment is needed in order to make the NMC a viable cosmological model.
