I don't think the Wargs cared for the canon, or for history, for that matter. As Mauan, son of Huan (yes, he was a Warg) once put it:
[Mauan: ]We are not concerned with history, with the past ages of Arda; for to our care was given all the notes and chords of the Music, to keep in order until it has reached the fullness of its measure and our Lord comes to cleanse it.
This is also the first time a Warg has mentioned "our Lord", or, as scholars name it, "
The Lord of the Wargs." Many say that this refers Argwë, brother of Varsur, the Viceregent of the Timeless Halls under Eru himself; in which case the "fullness of its measure" refers to that future time when Varsur and Melkor shall forcibly open the Door of Night and enter the World.
What do you think?