Sexism is not if you are being a nag and you get called a bitch as a result. The guy in the story just sounds like a jerk who wasn't taking his TA responsibility seriously.
Finally, even if there were sexism in that one CS departmenT it wouldn't mean that there's hidden sexism in CS departmentS. That's just stupidity and assumption.
Because one female had a problem in one CS department, she implies the same problem exists everywhere from Timbuktu to Helsinki?