Remember, Bruia chastised a Tanna for speaking to her two extra words. “
I believe (correct me if I am wrong) that the person Bruriah thus chastised was himself a vocal proponent of the idea of not speaking too much to a woman. She was likely giving him some sarcastic mussar.
It is NOT flirting or conversation with the opposite gender to day Good Shabbos as you walk by. If you stopped and continued the conversation, it possibly could be construed as such, if that is what one insists on thinking. But certainly not so, in passing.