It is not a good idea to assume that because something was in a book with "STAR WARS" on it that it is indeed tied into the movies or is GL's Star Wars. Remember, people pay GL for the rights to write a story under the Star Wars logo. These people write the books as they see fit, and a lot of times GL does not have any input in the book.
""As Maul and Sidious clearly discussed in TPM, the Sith have been after Revenge for quite some time, since their defeat at the end of the original Sith Wars."
....this was thousands of years before the PT."
So what? That changes nothing of what I have said.
BTW, as Mundi clearly says in TPM, *A* millenium, not several.