What is said in the mangas and some books isn't necessarily canon*, but what happens ingame totally is. I mean, I don't know how to phrase this correctly (english ain't my first language), but the "Warcraft Lore" would be irrelevant if this wasn't the case. That's like having a game like GTA 5 and whatever happens there isn't canon in the GTA lore (maybe that's not the best example). After all, the books (and other lectures) are based of the Warcraft Games (WC1,2,3 and WoW) and not the other way around (I am aware though.
That being said though, even if you were right... there is
no source that claims what OP said. He just pulled this out of his ass
* Mangas/Comics and RPG books are confirmed that they are not canon, while the regular books are complicated sometimes:
dccomics.com/media/podcasts/DCComics_2007-07-28_Wow_Its_World_of_WarCraft_San_Diego_Comic_Con_2007.mp3 (links broken unfortunately)
It's more of a: "some things are more canon than others"... either way, the game is always on top of this (If there is a Statement from Blizzard though where they say that the books [not a specific one, but generally] are more correct, then I'm taking this back ofc).