Only God is holy.... and he doesn't typically fire or excommunicate anyone. Men fire and excommunicate according to scripture.
In the literal sense you are quite correct. As we are told every Sunday at Mass: "You alone are the Holy One, You alone are the Lord, You alone are the Most High, Jesus Christ . . . all life, all holiness comes from You".
Of course, Scripture refers to many believers as "saints" (in the Greek hagioi or "holy ones"). It is in this latter, derived sense that the Pope is called holy.
St. Paul was not ascribing the transcendent holiness of God Himself to the "saints in Jerusalem". Nor am I to the Pope.