Aatrox Ult Buff

So i been using Aatrox alot lately and noticed he is easily counterable by anything that slows auto attack speed, ex frozen heart, ice born malphites W, wither and so on he just gets owned because he has no sustain or damage proc and i think and easy way to fix this is to make his ult ignore auto attack slows for its duration because whats the point of the extra attack speed if its just shut down by normal abilities. What do you guys think?