If she is being discriminated against, my guess is that the discriminating is being done by angry feminists who are angry at this woman precisely because she is attractive to men and they aren't.

Iguana, it may be a bit more something other than jealousy, altho that could figure in. The feminist ethos about women who dress in attractive clothes, wear make-up, and are noticeably sexy is that it represents a sell-out to stereotypically male-driven values, and deligitimizes the intellectual and professional recognition due to other women. Perpetuating the stereotype of a woman as a "pretty thing" whose job is to look nice, act nice, and not threaten or challenge men in any way.

In this light, the sexy librarian, by her appearance, would be seen to be helping keep women "down."

I don't agree, of course. There are plenty of Brainy Bettys (I'm, uh, married to one), recognized for their beauty and intellect. But I think the Womyn of Hah-vahd who've been keeping their pretty sister down, see it as a zero-sum game.

Not just "helping keep women down". She could be viewed as a threat to her higher-ups' jobs.

As a librarian, with a BA and MA in Medieval History, a BFA in music, and my MLS, I've lost two jobs in high schools because I was viewed as a threat by my bosses (and in one case this was recognized by the school admin). Dressing more dowdily might have helped (I don't dress particularly revealingly, but elegant and trendy have been used to describe my style), but the fact that I was very good at my job, and extremely well liked by both students and academic staff would have outweighed any benefits that "dressing like a librarian" might have confered.

So now I'm a solo librarian outside Academe, and no one complains at all.