Comment on Fermionic entanglement ambiguity in noninertial frames

In this Comment we show that the ambiguity of entropic quantities calculated by Montero and Martin-Martinez [Phys. Rev. A 83, 062323 (2011)] for fermionic fields in the context of the Unruh effect is not related to the properties of anticommuting fields, as claimed therein, but rather to wrong mathematical manipulations with them and not taking into account a fundamental superselection rule of quantum field theory.