Comment on "Observing a wormhole"

In their recent paper Dai and Stojkovic [arXiv:1910.00429] discuss an interesting possibility: a star near a wormhole mouth may gravitationally feel an object located near the other mouth. This means that a star’s trajectory may tell an observer that the star orbits a wormhole mouth and not a black hole. I argue that within the approximation used in the paper the effect is, in fact, unobservable irrespective of how accurate the measurements are.