He clearly writes against the heresy of Theodore so it is entirely reasonable to call the teaching of Theodore which he condemns - Theodoreanism.You could Father, but why wouldn't you use the word he (and patristic heresiographies) used:Nestorianism?
Fr. Peter can answer for himself, of course, but I always thought that the term Theodoran was appropriate because Nestorius got his heresy from Theodore and it was in Theodore's name that the heresy continued after Nestorus' condemnation.
It was, after all, the writings of Theodore, not Nestorius, that the Armenians presented to Proclus for his judgement, and that was the center of the ruckus we are discussing now. That is why the author referred to the Armenians at that time as "anti-Theodoran," rather than "anti-Nestorian." It was Theodore they were really dealing with, not Nestorius.
In other words, Nestorius was gone, but his heresy lived on in the name of his teacher.