Read the sentence -- it does not give an EITHER/OR false dichtomy denying the truth of one based on the truth of the other. Teachings as taught by word of Mouth from the Apostles are True as are teachigns as taught by letter from the Apostles.
"OR" means "pick one" if you say "Choose this OR that", but not if you say "You can learn calculus from the text book or by listening to the teacher" -- one does not negate the other
And that is the false dichtomy produced by the various solas -- God is not to be reduced to a false dichtomy.
"OR" means "pick one" if you say "Choose this OR that", but not if you say "You can learn calculus from the text book or by listening to the teacher" -- one does not negate the otherBINGO...We have a winner...
You can learn calculus by listening to the teacher...OR, you can learn calculus by the book...BUT they must teach the same thing...The calculus teacher must teach orally what he read from the book...OR, the book must be written to match what the teacher taught...
Of course you'll never admit it but you explained how oral tradition is the same as the written words...If you can chose one or the other they must be the same...
And if you claim what is not true, that you were given the oral tradition AND the written word, you could have a case in your favor...But that's not what the scripture says...