Hello, first time posting.
An interesting theory indeed. I agree with your theory regarding Jude’s use of the two non-cannonical sources. There are several non-cannonical sources that have use for teaching, meditation, and prayer.
As a further example of “sound logic” using sources not found in the New Testament, refer to Pope Bennedict’s small book on The Apostles. He uses the Didache as a source as well as another source I cannot recall off the top of my head. The letters of Ignatius and Poycarp also contain great material. Just because they did not meet the original tests for inclusion into the New Testament in particular does not mean that they do not have good food for the soul. But I digress from the original point.
I concur with your theory that it was divinely inspired and accurate. Remembering that it was written by divinely inspired humans as Dei Verbum instructs us, the companion piece to this epistle 2 John avoided its use as it became not in vogue to use these noncannonical sources.
Hope this contributes to the discussion.
Brad