I think we could add more of Paul's words to this discussion, like him saying that "All Scripture is inspired of God". He probably had no expectation that his letters would ever become part of scripture when he wrote that. Yet they are. Even stuff like him leaving a cloak at Troas or asking for 'the parchments' has some special relevance or ends up being quoted in a WT, when it was entirely mundane.
Same as always, the GB's basic message is that it doesn't really matter what the Bible actually says, what matters is what we tell you it says.
--sd-7