That would be true if the policy gave women 16 weeks and men 8 weeks, regardless of whether or not the woman gave birth. But, as reported, if you did not give birth, for example if you adopted a child, you only get 8 weeks: even if you are a woman.

A larger point could be made that it's somewhat pointless to speculate about whether a policy is sexist when we're hearing a brief summary from a secondary source. A large aspect of this is how the policy is actually worded and carried out in practice.

This is "disparate impact" and is fiercely debated where it appears.