They can't expect media to NOT be sexist when viewers are sexist. If people can't watch a woman deliver the news, then guess what - they won't hire one.
How do they know, though? I'm never asked, that's for sure. I'd have said keep the female anchor, I like her and the guy is kind of annoying. But I don't think they do ask, I think they just assume.
On the other hand, when women are criticized for being pregnant on air or showing their arms, I guess that's enough evidence of public sexism.
Next, there will soon be emancipation for ugly people. Just watch.
Can't wait! A movement I could actually benefit from!