IIRC, the last we got of her from RJ's pen was her experience of the Cleansing. I can't recall if she was in KoD, for some reason. However, the last we saw of her, it implied she might have had a transformative experience from the sheer quantity of terror she suffered. She could be experiencing a kind of flipped form of PTSD, whereby she feels that surviving a near-encounter with the Choedan Kal means a mere Forsaken isn't worth being afraid of.

Another reason could be the apparent lifting of her restrictions since then, being allowed to wear her own mindtrap, if I read the scene right. Or a combination of the two.

None of this speculation, of course, undermines the criticisms of Sanderson in this thread. Rather it just goes to show another way the series is suffering, because all we have are hints of a significant character transformation, that may lead Moghedian to do something extraordinarily out of character in aMoL that will seem ridiculous and coming from left field, when it was simmering all along.