ben: You didn’t address all of LevAryeh’s points. Shulchan Aruch rules in this matter l’halacha. That is relevant today. The following Igros Moshe is also speaking of today’s generation:
To Rav Elya Svei shlit”a, Rosh Yeshiva of Philadelphia,
Regarding the issue that there are some girls schools that are called Bais Yaakovs and the like, where the administration and the teachers of the school want to teach the girls Mishnayos: Behold, in the Rambam Talmud Torah 1:13 he rules like R. Eliezer in Sotah 20a, that you may not teach girls Torah. Yet he distinguishes between Torah shebal peh, which, if you teach to girls is as if you taught them tiflus, whereas Torah shebiksav is not as if you taught them tiflus, but l’chatchilah you shouldn’t teach it to them anyway. In any case, Mishnayos, which is Torah shebal peh, Chazal commanded us not to teach to girls, and if you do, it is as if you taught them Tiflus. Therefore, you should prevent them from doing this [teaching Mishnayos], with the exception of Pirkei Avos, which, because it discusses mussar and good midos you may teach it to them with explanations in order to awaken them to ahavas hatorah and good midos, but not any other Mesechta. And because this issue is simple I will end here with a blessing that you may spread Torah and Yiras Shamayim to the world.
Your friend,
Moshe Feinsten