  Recently Guerout et al. [Phys. Rev. E, v.93, 022108 (2016)] advocated that
the lossless plasma model has to be redefined as the limit of the Drude model
when the relaxation parameter goes to zero. It was claimed that the previously
used plasma model cannot correctly describe the Casimir pressure between two
plates made of both nonmagnetic and magnetic metals and has to be replaced with
the redefined one. We show that the suggested redefinition does not satisfy
necessary physical requirements imposed on the dielectric permittivity. We also
present a plausible explanation to the fact that the lossless plasma model
describes the Casimir pressure correctly even though it does not match the
optical and electrical properties of metals.
