One,
Adn if more than one scholar from differente backgrounds agree. What is known about those scholars?
From the link I gave you can get to several different introductions to the Pastorals (1-2 Timothy / Titus). Afaik only fundamentalist Protestant (Evangelical) or traditionalist Catholic scholars would still attribute them to Paul. Most mainstream Catholic scholars have given up this traditional option since the 1970's (in France Ceslas Spicq was one of its last advocates in the 60's).
Euphemism,
The expression "all scripture" (pasa graphè) in 2 Timothy is remarkably open and undetermined. To refer to a definite body of literature one could expect at least the use of the article, pasa hè graphè, which would mean "all the scripture" or "all Scripture" (which scripture being defined by the capital in English).
The 2nd-century Christian Church was quite busy in defining a NT canon by choosing between Christian works. The reference in 2 Peter 3:15f to a collection of the Pauline letters "which the ignorant and unstable (i.e. Marcionite?) twist" is a very good example of that preoccupation. Defining the OT (or, more exactly, the Hebrew Bible) canon was rather the worry and business of the Jewish pharisaic-rabbinical community. Both were separated, and non-canonical Jewish works were seen as a threat to Judaism, not Christianity. As the diverse contents of Christian LXX codices shows, the Christian OT canon was still widely open in the 4th and 5th centuries and it was not dogmatically fixed before the 16th-century Reformation (which adopted the Jewish rabbinical canon) and the subsequent Catholic Council of Trent (which adopted a wider canon including the deuterocanonical books).
In the NT, the formal authoritative quotations ("Scripture says" or "it is written") do include a number of texts which do not belong to either (such as 1 Enoch quoted verbatim by Jude, or perhaps the Book of Eldad and Modad quoted by James 4:5 -- see Leolaia's recent thread on this one).