This is a Sola Scriptura argument. You can't trash the Protestants while clinging to the same thing yourself. If the the rock argument was really true to Christ's teaching, the Sees of Constantinople and Antioch and others would still have been in communion with Rome.

Edit: plus St. Peter also founded the See of Antioch. What makes Rome the keeper of the key and not Antioch? Just because Rome was the larger metropolis? That's a politically charged and thus scummy argument.

This is a Sola Scriptura argument. You can't trash the Protestants while clinging to the same thing yourself. If the the rock argument was really true to Christ's teaching, the Sees of Constantinople and Antioch and others would still have been in communion with Rome.