Your analogy is hopelessly flawed; you just made Roger into a Pope.
A more correct analogy would be the Predident sending you a toolkit along with a note saying all the tools in the kit are trustworthy. No one is disputing that. Without a note from the President stating you won't need any other tools, the trustworthyness of the tools is irrelevant to the question at hand.
If scripture is an authority, and claims to be the final authority before God Himself, above all people, then it either is not really an authority, or is what it claims to be.
Where does it claim final authority?
Where does it claim final authority?
Matt 24:35, Acts 17:2, Acts 17:11, 1 Thess. 2:13, 2 Tim. 3:16 for starters. Think about it. What would the final authority be below God if not His Word? If scripture is truly inspired by God, then it must by definition be the final authority and no one below can contradict it. Appeals to scripture are final appeals. Take the whole book of Hebrews as an example.