You won't get this Catholic to deny the divine nature of the letters to Timothy, but how do you reconcile that, at the time it was written, the New Testament did not yet exist nor was there an Old Testament canon universally agreed upon by all Jews? Further, how do you reconcile it against itself which was a teaching based upon tradition?
It says all scripture, so once scripture was complete, we had what we needed. The divine authority of the Apostles, who wrote scripture, was then finished. There is no need for a new Apostle, to reveal more, since the Apostles finished their task.
As Peter put it:
16For we did not follow cleverly devised myths when we made known to you the power and coming of our Lord Jesus Christ, but we were eyewitnesses of his majesty. 17For when he received honor and glory from God the Father, and the voice was borne to him by the Majestic Glory, "This is my beloved Son, with whom I am well pleased," 18we ourselves heard this very voice borne from heaven, for we were with him on the holy mountain. 19And we have something more sure, the prophetic word, to which you will do well to pay attention as to a lamp shining in a dark place, until the day dawns and the morning star rises in your hearts, 20knowing this first of all, that no prophecy of Scripture comes from someone’s own interpretation. 21For no prophecy was ever produced by the will of man, but men spoke from God as they were carried along by the Holy Spirit."
Their first hand experience with Jesus was wonderful, but they left behind "something more sure, the prophetic word".
"how do you reconcile it against itself which was a teaching based upon tradition?"
"But as for you, continue in what you have learned and have firmly believed, knowing from whom you learned it..."
Timothy learned from the Apostle Paul. I'd be willing to accept his authority, but I won't give his authority to the doctors of the Catholic church - the Magisterium - who go beyond what the Apostles taught.
Paul told the Ephesian elders:
25And now, behold, I know that none of you among whom I have gone about proclaiming the kingdom will see my face again. 26Therefore I testify to you this day that I am innocent of the blood of all of you, 27for I did not shrink from declaring to you the whole counsel of God. 28 Pay careful attention to yourselves and to all the flock, in which the Holy Spirit has made you overseers, to care for the church of God, which he obtained with his own blood. 29I know that after my departure fierce wolves will come in among you, not sparing the flock; 30and from among your own selves will arise men speaking twisted things, to draw away the disciples after them." - Acts 20
Paul taught the whole counsel of God. There was nothing more the Magisterium needed to reveal. Nor did men have any business trying to add to what the Apostles taught:
"9Everyone who goes on ahead and does not abide in the teaching of Christ, does not have God. Whoever abides in the teaching has both the Father and the Son. 10If anyone comes to you and does not bring this teaching, do not receive him into your house or give him any greeting, 11for whoever greets him takes part in his wicked works." - 2 John
If we were to abide in the teaching, then it didn't need additional revelation from church doctors. On the contrary: "If anyone comes to you and does not bring this teaching, do not receive him into your house or give him any greeting, 11for whoever greets him takes part in his wicked works."
Paul didn't advise Timothy to follow the traditions of man, but to follow what he received from the Apostles, and that which, by the will of God, was turned into scripture - which Peter said was more sure than his own memories of Jesus Christ. "For no prophecy was ever produced by the will of man, but men spoke from God as they were carried along by the Holy Spirit."
"nor was there an Old Testament canon universally agreed upon by all Jews?"
By all Jews? No. By Jesus and the Apostles? Yes. When Jesus and the Apostles said, "It is written...", they didn't confine themselves to the Pentateuch. They accepted the whole of the Old Testament, yet they never cited the Apocrypha for authority.
For example, in Mark 1 we read, "As it is written in Isaiah the prophet..", so we know the Apostles accepted Isaiah as authoritative. You won't find "It is written..." said of the Apocrypha, which is why we know the Jews rejected it - in the time of Christ - and why many Catholics taught that the Apocrypha was good for public reading, but not for doctrine, and why the Protestants took that Catholic teaching to heart and rejected it as scripture - for scripture itself says real scripture is "useful for teaching, rebuking, correcting and training in righteousness".