Someone asked the rabbi about using Mezuzos written by a Sofer Stam, Moshe Tzarum (משה צארום), who studied under Rabbi Yichya Kapach himself, and an avowed subscriber to the Dor Deah idea. Rabbi Zilberman responded there is no question of heresy in denying the Zohar. They themselves miss out, no more.
Rabbi Yehuda Epstein (editor of Kedushas Tzion) heard the above from a Jew he trusts and gave me permission to publicize this.