> the story was massively pinned everywhere as one of sexism, when the main conflict involved another woman, and then the man who reversed Horvath's commits appeared to hold a grudge, not necessarily sexist attitudes.

That is not true, that's just what the nitpickers here focused on. To quote the TechCrunch story:

Horvath claims: “I had a really hard time getting used to the culture, the aggressive communication on pull requests and how little the men I worked with respected and valued my opinion,” she wrote in an email to TechCrunch.

Why did Horvath work for GitHub? She “loved the idea of GitHub because it was the place people went to make things for people who make things.”

In light of that, Horvath told us that she “participated in the boys’ club upon joining,” but when her “character started being discussed in inappropriate places like on pull requests and issues,” the situation changed.

In short, Horvath said that she felt she was being treated differently internally simply due to her gender and not the quality of her work. She calls her colleagues’ response to her own work and the work of other female GitHub employees a “serious problem.” Despite GitHub hiring more female developers, Horvath said she struggled to feel welcome.