Maybe it's me, but I find this very unpersuasive. If one is to apply the tzniyus argument, one must apply it consistently. If it precludes women from serving as Rabbis, it precludes women from serving as lawyers, as professors, as businesswomen. I don’t think Stern College is about to shut down its pre-med and pre-law program, nor has anyone suggested they do so. Why the double-standard?
Why was it so obvious to the tanaim that we can not have women rabbis? After all, Tosfos (Bava Kama 15a) raises the possibility of giving semicha to women, and having them serve on a beth din. So if women can possibly receive semicha, why can’t they serve the community as rabbis?
The answer is obvious. Although we must sometimes compromise on our midas hatznius and do certain mitzvos befarhesia (in public), this is not required of women. Women are not being discriminated against. They alone, unlike men, are given the opportunity to maintain their midas hahistatrus at all times.
Rashi in Devarim who writes that there was never a hava amina of appointing women judges can easily be interpreted as simply reflecting social norms common for that period, not halachic restrictions. Were tzniyus reason alone to dismiss a woman from serving as judge, one would have expected Tosfos or any of the other Rishonim who discuss the admissibility of Devorah to raise the issue – yet none do. Tosfos (B"K 15) is not discussing the theoretical possibility of giving semicha to a woman for her to hang as a diploma on her wall, but rather is discussing the reality of a woman serving as judge.
In the tshuvah by Rav Uziel I cited in the previous posts ( Mishpitei Uziel C.M. 6, link) he notes that women on a day to day basis engage in commerce without anyone objecting. “Al tarbeh sicha” restricts only frivolous, unnecessary speech, not professional interaction. If we do not limit women’s professional pursuits because of concerns for tzniyus, kal v’chomer we need not impose limitations when they are involved in klei kodesh, in activities that aim to strengthen Torah.
Rav Yehudah Herzel Henkin (Shu”T Bnei Banin I p. 202) in an essay entitled, “Mekomah Shel Isha” notes that the description of the eishes chayil portrayed by Mishlei is a women engaged in commerce, in providing for her family – not the stay at home mom. While not every woman can successfully be the ideal eishes chayil, that does not mean there is a prohibition against aspiring to do so. A recent news item celebrated the appointment of a frum woman judge to district court in Baltimore. It does not seem that the frum world shuns her for her achievements, but to the contrary, celebrates her ability to balance her religiosity with her involvement in the public sphere.
I am sure some will react to my post by saying, ain hachi nami, women should better be at home than in the workplace, and indeed, we should bar them from all professions, not only the Rabbinate. I credit them for at least being consistent, but don't see their attitude as realistic. Tzniyus while at work is certainly required, for men as well as women, but I do not think the requirement for modesty can be used to preclude professional aspirations entirely.