I’d like to point out that if we go based on the reason the gemara(in bavli) gives, which is that women are מוציא דברי תורה לדברי הבאי, that it is our halachik responsibility to not do things which lead to bizayon hatorah. If a woman learns on her own – even according to those who allow it in din, is she not likewise responsible to not do something which will lead to bizayon hatorah? If she indeed is an exceptional woman, refined in mind and middos, like bruriah, then she, knowing herself and her capabilities, will not make Torah into divrei havai.
But if a woman is not on that level and she does so, maybe the men aren’t obligated to stop her, as their obligation would be just not to teach them and cause it by their actions, but the bizayon hatorah that the woman creates when she learns and turns Torah into divrei havai is fully, squarely on her shoulders. She has violated a grave sin in her study, not a mitzvah. And that’s the reason why the rambam says that a woman only has schar by torah she’biksav, and has no schar by torah shebaal peh, because he is referring to the vast majority of women who are incapable of such study and will perforce make divrei Torah into divrei havai.
That also leads us to another question – if most women were incapable of gemara study in the times of chazal, when people were purer and holier, to the point where they would make it divrei havai…. today’s women are any better? We’ve only dropped in our madregos since then.
And should it enter your mind to say that “todays women are smarter!” – that’s a prime example of divrei havai right there.