I am quite sure I remember reading, or hearing of a rather witty response by St Dioscorus to the Empress' remarks. As far as I remember, St Dioscorus refers to the fate suffered by Empress Eudoxia as a result of her treatment of St John. His response was something to the effect of: "You are referring to the act of your mother against St John in your effort to persuade me? Are you not forgetting what happened to her as a consequence?" If it's not in the Panegyric then it is certainly somewhere else; I can't be imagining it!
I will look for the PG volume you want once I resume my studies.
"Come and incline your ear to the voice of your Mother who gives you life by the sweet music of her voice. Come and suck the sweet milk of Orthodox doctrine from the living breast of the Mother who bore you" - St Philoxenus of Mabug