The author writes as if the only disagreement with purported Petrine Supremacy comes from so-called Protestant quarters, but even a cursory review with an unbiased eye demonstrates that not just Protestants but Eastern Orthodox and even Augustine, Origen and Chrysostom agree, that “the rock” was not the man, Peter, himself, it was his profession of faith, upon which the Church was to be built.
424 Moved by the grace of the Holy Spirit and drawn by the Father, we believe in Jesus and confess: 'You are the Christ, the Son of the living God.' On the rock of this faith confessed by St. Peter, Christ built his Church. "To preach. . . the unsearchable riches of Christ"