And raging on Tumblr is?
Look, if there's some deeply embedded injustice going on, here, it's not evident from this single exchange.
If this single exchange is part of a broader pattern with this person, that's something a manager and HR can help deal with, and you would be very well advised to keep cool in order to avoid escalating the situation further. Maintaining the moral high-ground isn't just about ideals, it's also practical advice for winning out in an exchange like this.
If this exchange is part of a larger, company-wide or societal trend, speaking about it rationally is still the better course as, right now, it's very hard to take this person seriously. Without additional context, this just looks like an insecure 20-something who's just struggling with their first workplace confrontation.
To some up: I can think of no scenario where behaving as this person has done will improve the situation, whether it's a one-off, or something systemic.
Edit:
Incidentally, it's entirely possible that this person raged out on their blog as part of processing this whole thing, then stepped back and started looking for a constructive path forward.
If that's the case, great.
Everything I've written, here, presumes that this post represents their definitive reaction to the situation, which may be entirely unfair.