What “heresy” would that be?
The Russian position (as described in the article) seems to me shot through with problems. First of all, the Rublev ikon *is still a bodily representation of God the Father*. Cloaking it in angelic garb does not change that.
Second of all, though yes, the full bodily representation of the Father is a quite late artistic development, the “Hand of God” motif for the Father is present from earliest Christianity and even Judaism from the Dura-Europos synagogue to today (my Jewish in-laws have it in their house).