Personally, I believe this tidbit was written by Sanderson. My biggest reason for believing so is Mesaana, specifically when Mesaana says (not the exact quote) "My followers infest the Tower like a plague." I don't know, but that really doesn't sound like Jordan's style to me. Jordan was never a fan of speeches, and this is far too "speechy." Furthermore, Graendal's creation of a hierarchy among the remaining Forsaken bespeaks Brandon. Jordan always kept this vague, and Graendal's explicit statements smell of fan-fiction to me.

Moridin is certainly playing with Graendal - vice-Nae'blis? Please! He knows Graendal's abilities, but he also is all too aware of Rand's strength (over-poweredness). Graendal is going to be defeated (unfortunately) though not before royally f'ing with Rand. I think that Rand's breakdown is going to directly involve Graendal and Cadsuane.

Demandred is as lame as ever.

Moridin generally uses zombie servants, and so him not using them here is significant. Graendal notes that Moridin has his cronies patrolling outside, specifically to defend against creatures of the Blight. Frankly, non-channelers wouldn't stand a chance, so I think its fairly obvious that these are Asha'man or at the very least Darkfriend channelers.