Differentially rotating scalarized neutron stars, mimickers of binary mergerremnants, can possess an enormous angular momentum larger than what couldpossibly be sustained in a neutron star in general relativity by about oneorder of magnitude. A natural question to ask is whether these solutions arestable and thus can realize in a binary coalescence. With this motivation inmind, we examine the criterion of dynamical stability against axisymmetricperturbations for these ultra-rotators by numerically tracking their nonlinearevolution in an axisymmetric setup. We demonstrate that the turning-pointcriterion still serves as a sufficient condition for asymmetric (in)stability.Our findings open an interesting question of whether the merger of twoscalarized neutron stars can produce (possibly short-lived) ultra-highlyrotating merger remnants.<br
