My understanding has always been that Catholic and Orthodox believe that the Holy Spirit guides the development of Tradition, but that this is guiding interpretation. It goes back to the Apostles. With a direct pipeline to God, you don't need the Apostles and you don't need Tradition. (For that matter, you don't need Jesus' teaching.) You get it directly from God.
All three traditions believe that the Holy Spirit is guiding them. Catholics make that explicit in the concept of Tradition. For the Reformers Scripture has its special role because the Holy Spirit speaks through it. (Indeed for Luther, it is through the preached Word -- and the Sacraments -- that God is present with us.) It's certainly possible that Orthodox believe something else, but I'd be surprised not to have heard about it before.