This all goes on the baseless assumption that the original author is a male. If you look through the user's archived talk pages, there are many indications that the user is actually female.
There's no evidence that women are less sexist than men. In fact, all the evidences is that women and men discriminate equally against women:
http://ideas.time.com/2012/10/04/womens-inhumanity-to-women/
Of course, this does show the flaw of trying to judge the gender of a person by how they present themselves online; while on average men and women may show small differences in communication, there are of course many women that communicate in a "men's" manner and v.v.
I love this: so we can fire sexist stereotypes at will, because if we see examples of men or women not fitting the stereotype, it is just a man acting like a woman or a woman acting like a man, so it doesn't count? Or in fact a woman acting like a jerk would be "acting like a man" and therefore reinforce the stereotype of men being jerks?