WIY: I don’t want to get into this again. Let’s just say that in some communities (mostly out-of-town) it is impossible for the men and women not to interact, at least on a minimal level. Thus, not saying “Good Shabbos” would be a tremendous insult and a violation of being Makdim Shalom to someone else. In other places, it would be Assur to wish a “Good Shabbos”.
I once heard a very good explanation for “Al Tarbeh Sichah” by a very Chareidi Rosh Kollel who had just spent a week visiting relatives in a small community. He says the Lashon is “Al Tarbeh”. So first, you have to be normal. You have to talk as much as is normally accepted wherever you are (which, he said, should never be more than “Hello”, “how are you doing”, “how are the kids”, etc. in a Frum place). And after you have reached the normal level of passing conversation, “Al Tirbeh” (and then he went on a long discussion of whether “Al Tirbeh” means Kipshuto or whether it means nothing at all and connected it to the Machlokes Rishonim about what M’ma’atim B’simcha during the nine days means.)