Do you have a citation that mothers at Yahoo complained? Or that mothers at Yahoo were non-trivially worse off than other companies in their situation at that time?
Yes, the link 'antt posted goes into it by the third sentence.
"This upset many employees – mothers in particular."
As for other companies, well, my employer existed at that time, had and still has a work-from-home culture that's more friendly towards mothers, and is routinely highly rated in most innovative company beauty pageants. The link from the link also details basically every other company in 2013 having a non-trivially better situation with flexible WFH policies.
You can't justify sexism with "hey look she did something bad for mothers". The merits of the article have nothing to do with what's wrong with your comment.
You can't justify 140 hour work weeks with accusations of sexism.
At some point you need to face the fact that you are a useful idiot to the lizard class by only seeing sexism, even when women are being worked to death by other women.
You of course would know this if you read the link I provided, instead of the first line of my post.