It does not such thing. It says that Bishop Timothy will be fully equipped for his work if he supplements his formation with the study of the scripture. But Paul says so only after he exhorted him to heed the lessons St. Paul and apparently others gave him orally (2 Tim 3:14). Likewise, the Catholic Church teaches that one can profit from reading the scriptures if such reading is combined with solid catechism.
It does not such thing. It says that Bishop Timothy will be fully equipped for his work if he supplements his formation with the study of the scripture. But Paul says so only after he exhorted him to heed the lessons St. Paul and apparently others gave him orally (2 Tim 3:14).
He is only supplementing the OT with what he is now learning as what would become the NT. There is nothing in this verse that says he is being taught extra-Biblical teachings and traditions. That is only a presumption that you are making. Timothy did not have the NT at the time as we do now. Paul was telling him to hold on to the teachings that would become scripture, not other teachings. By "EXTRA", I was saying anything outside of what we call the Bible today. Extra-scriptural teaching does zero to make a man thoroughly equipped, only scripture makes him so.