Okay, it seems that they believe discrimination to be a non-issue. My bad. However,
And I'd imagine that mothers are treated that way, because they have a child and thus can't be trusted to be as reliable or willing to work as much as a non parent. Then you throw in the maternity leave possibility and stuff and they become an undesirable employee. In the same vain, fathers are less desirable than a non parent. And then there's always age to take into account.
The study clearly shows that fathers do not have the same problem mothers do, not even ones that take paternity leave. How is that not the definition of discrimination, and therefore sexism? Also,
You can't even really expect to know how someone will react so basing it off gender and biology isn't that bad..
But this is the absolute, by-the-book definition of sexism. There is nothing more sexist than making a clear distinction between the capabilities of men and women in the workplace based on gender.