Then why give Azshara the weapon to kill N'zoth?
She mentions "the hungering maw" but not that she's in favor of it. Just that she wants more undead soldiers, as being undead is one of the few ways souls get saved from oblivion in this universe. The hungering maw is the oblivion she's been trying so hard to avoid.
The bombing thunderbluff thing was just a fan theory that turned out to be bullshit