as it wasn't a discussionIt never got the chance to be a discussion, as the author responded to the opening volley with a shotgun blast.
That's his prerogative, of course, as it is his blog, and he can take his ball and go home if he wants to.
The cause of women in computer science (which as student of a CS department, I wholeheartedly support) is not helped by people derailing everything in the manner in which the commentator did.
It's not a derail. It is a topic which came up because of language the author used, and which is an ongoing problem in the community of software developers. While you are free to believe in a platonic ideal of "pure ideas and discussion," it doesn't exist in this messy world of relationships and human language and politics. If you are still a student, I suggest you take a gender/sexual/racial politics course and try befriending some people with very much opposite viewpoints to your own. You may be surprised at your shift in thinking.
But leaving that aside for the moment, let's say the author's main intent was to "nip that derailing in the bud." What do you think the most effective, least hurtful way to approach that would have been?
1) Ignore the comment,
2) assuming he is the administrator of the WordPress blog he writes on, delete/hide the comment, or
3) lash out in a juvenile, sexist, hateful fashion.
I'm going to go with 1 or 2 being better than option 3 any day of the week.