  In a recent work [arXiv:1301.3960], Bamba and Ogawa developed a microscopic
model describing the field of a photonic cavity coupled to a matter
exciton-like resonance. One of the results they obtain studying such a model is
that, in the ultrastrong coupling regime, usually safe approaches can give
wrong results for the dissipation rates of the polaritonic excitations. In
particular the dissipation rates calculated applying the rotating wave
approximation on the system-environment coupling qualitatively differ from the
ones calculated using a microscopic theory based on the quantum electrodynamics
for dielectric media. Here I show that this result is an artifact, caused by an
inconsistent application of the rotating wave approximation and by a
questionable parameter choice.
