[Garfie]

I don't think she's dumb, but merely being told she is by Lotan because he can't seem to abide a woman who has a point of view that differs from his, and dares to challenge him.

He's calling her dumb, and trying to make her feel stupid, in an attempt to make her reluctant to speak out against him in future. It doesn't make her dumb just because Lotan says she is.