I cant see how it's not discriminatory based on sex.
The woman was treated differently, purely because of her sex. It's the definition of sex discrimination.
"Different types of sex discrimination
There are four main types of sex discrimination.
- Direct discrimination
This happens when, because of your sex, someone treats you worse than someone of the opposite sex who is in a similar situation. For example:
a nightclub offers free entry to women but charges men to get in"
It's not about deciding whether or not she should have been offended. It's whether she was treated differently to how a man would have been, in the same situation. And the answer is yes.