Health: Yes, well that “whatever reason” can make a tremendous difference, can’t it? Or do you think that every “MO”, as you put it, is a Mumar Lehachis on the Issur Asei of Tznius? Oh, and before you call my understanding of Halacha ridiculous you might want to bring up a source to back up your assertion. Until you can prove that these women violate Tznius (I will admit that I am unsure about this, does being a Mumar to be Mevatel an Asei Lechachis even make you a Mumar L’chol Hatorah Kulah?) and that they do it Lehachis, you have no claim here.
Have you ever thought that maybe, just maybe, because they keep Shabbos and Kashrus properly they also have a reason to consider what they are doing keeping Tznius properly?