Published in Journal of Mathematical Physics, 2017 by Hau, Oberlack & Chagelishvili. Apart from several technical mistakes and inconsistencies (please see Sec.4 in https://arxiv.org/abs/1712.03105 ), this study, initiated and supervised by M. Oberlack, is seriously misleading. Their claim that they have derived "a generalized approach" to stability analysis for unbounded shear flow that "unites both – the nonmodal (Kelvin mode) and the modal – approaches" for which "the class of solutions is much wider than the well-known Kelvin and modal solutions" is not correct and therefore misleading. First, their self-defined "modal approach" and "Kelvin mode approach" are complementary approaches, namely in being a pure temporal and a pure spatial approach respectively, which exclude each other and which therefore cannot be "united" into a single universal approach — this flaw is discussed in detail in Sec.4.2 in https://arxiv....