"Using sexist language in educational materials today produces a body of workers that will be active in the workforce for decades that thinks that sexist language is professional."
Indeed.
Indeed.
The larger and more important issue is the utter contempt for feminism (which, at its best simply strives to have women be treated no worse than men), and the contempt for "social justice people" (ie. people who actually care about justice for everyone).
And this contempt came from someone who feminists and "social justice people" were concerned with helping. Instead of any kind of constructive or even thoughtful comment on the issue, the author's friend simply contemptuously dismissed her and everyone who cares about any of these issues.
That's the larger problem. Contemptuous dismissal of people who are actually interested and motivated to help move society forward.
"I'm here to save you from unfair gender association because it's unprofessional!"
Really? That's the story? That's what is supposed to persuade people to support your cause? How do you associate that with real problems? Who is hurt by this? What is the solution and why is it better? How does this help me personally, and society as a whole? Those are the questions that need clear, simple and concise answers.
But they're not completely (or perhaps even largely) to blame. What most people know about feminism and "social justice" comes not from feminists or "social justice people", but from the media.
That's probably why the poster's friend off-handedly and contemptuously dismissed her concern. There's a ton of conservative and reactionary backlash against both feminism and social justice in the largely conservative-dominated media in the US.
So it's really not that surprising that expressing concern about these issues would garner such a negative response. It is sad, however.