I would ask what scripture he thinks that passage is refering to. We did not have a Bible till the 300’s…but…that aside…
He is right, in the sense that all we need to know is in the bible and I would say, also, in Sacred Tradition. BUT! By who’s interpretation?
2 Peter 1:20-21 “First of all you must understand this, that no prophecy of Scripture is a matter on one’s own interpretation, because no prophecy ever came by the impulse of man, but men moved by the Holy Spirit spoke from God.”
2 Thess. 2:15 “So then, brethren, stand firm and hold to the traditions which you were taught by us, either by word of mouth or by letter.”
2 John 12 “'Though I have much to write to you, I would rather not use paper and ink, but I hope to come to see you and talk with you face to face, so that our joy may be complete.”
St. Vincent of Lerins (434ad) …quite plainly, Sacred Scripture, by reason of its own depth, is not accepted by everyone as having one and the same meaning…it can almost appear as if there are as many opinions as there are men.
On the question of Mary, I’m not sure. I would have to know more about the old laws. I’m sure Scott Hahn would have the answer!(hahaha)
Just as a side note, I am a Baptist convert.