Nonsense!
Grossberg & Mingolla's model is presented as a specific neurophysiological model that accounts for a number of illusory phenomena. To suggest that their model was neurophysiologically motivated, and was only discovered later to also account for illusory phenomena as if "by accident" is both absurd, and totally irrelevant.
Contrary to the reviewer's contention, there is no difference between a model "designed to account for illusory contours", and a model "whose design was influenced by the properties of illusory contours". The reviewer is drawing a distinction without a difference.
Furthermore, a model of perceptual phenomena is by no means invalid if the phenomena for which it accounts are known before the model is formulated, or if the model is specifically designed to account for those phenomena. Sure the generality of the model is put to a greater test by trying it later on different, or even newly discovered phenomena. But the observed properties of Gestalt illusions are already so complex and perplexing that any model that can successfully account for a significant subset of those phenomena already represents a significant contribution to our understanding of the principles behind illusory contour formation.