I think her personal friendship with the Ronell is blinding her to the realities of the case. I think it's unfair to say that she "doesn't understand" these kinds of power dynamics. She's just human like everyone and she's made a terrible mistake signing this letter.
I should be clear: I'm a huge admirer of Professor Butler, and her writing has been very meaningful to me personally (though i recognize that many HNers might disagree). I still admire her greatly, but it just makes the disappointment so much greater. She should know better than this.