Problem of stability of charged particle dynamics in the Penning-Malmberg-Surko trap is considered. It is shown that, magnetron motion is unstable for sufficiently small value of parameter a (which is the amplitude related parameter of the Rotating Wall (RW) electric dipole field). This contradicts the conclusion of the article [1] that there is a possibility of the compression of magnetron motions in the case of | a |→ 0. So it may indicate that the simplified model of the dynamics used by the author of the article is not accurately enough to describe the dynamics of the original system. Copyright © 2017 CC-BY-3.0 and by the respective authors