Why do you think this? Most employment in California (at least from my personal experience) is "at-will". Either party can terminate at any time with no notice and with no cause.
Also in this case the reasons have nothing to do with her gender, but more that she failed at her job at being a developer evangelist.
At will employment does not protect against wrongful termination due to discrimination or retaliation[1]. It's obviously going to be up to a number of lawyers to figure out if there's a strong case for that to be made here.
Also in this case the reasons have nothing to do with her gender, but more that she failed at her job at being a developer evangelist.