That's not the reason, and you know it.
"On the one hand, it seems ridiculous (absurd, perhaps) to fire someone over a pronoun -- but to characterize it that way would be a gross oversimplification: it's not the use of the gendered pronoun that's at issue (that's just sloppy), but rather the insistence that pronouns should in fact be gendered."
https://www.joyent.com/blog/the-power-of-a-pronoun
The biggest issue is the way that you handled this. You did this appallingly. You still seem to be puzzled why people still bring this up.
In a community project, people often do things you aren't going to like. Ben rejected a push, and he steadfastly maintains that he did this for good reasons:
https://github.com/joyent/libuv/pull/1015#issuecomment-29568...
Now instead of communicating with Ben, giving him the benefit of the doubt as a non-native speaker of English and calling him out publicly in the way you did was an absolute classic case of what you do NOT do.
In a community run project, the dynamics are different to being in a corporation. The first rule is: you are dealing with a lot of people, from a lot of different backgrounds. There is lots of room for misunderstanding. The absolute golden rule around dealing with a popular project is to try to wrangle this appropriately and with as little heat as possible.
So let's review what you did:
1. You posted one of the most inflammatory, aggressive posts I've seen in a very long time. You took no time to talk to Ben about his position and to talk him around to making an apology and reversing his decision.
2. You compete with StrongLoop. You basically told your competitor that they should fire one of their best developers to the project. Your company may have been a main initiator of Node.js and you see it as largely the steward for the project, but your own employee reversed the decision of a major contributor.
And this is where you really stuffed up. For some time there had been rumblings about how Joyent was biased about the way they accepted commits and directed the project - rightly or wrongly. There was a perception of bias towards Joyent's interests. That's not necessarily a correct viewpoint. But you started a chain of events you now can't control.
Joyent has finally setup a Foundation, but has now got a fork competing with the core project. StrongLoop is one of the groups backing io.js. A large number of your core developers are publicly backing io.js.
3. Community leaders, like yourself, aren't meant to send abusive messages over blogs. You called him an arsehole. You called for his sacking.
Let's underscore how tone-deaf you have been, and completely clueless over how to run an open source project:
"While we would fire Ben over this, node.js is an open source project and one doesn't necessarily have the same levers. Indeed, one of the challenges of an open source project that depends on volunteer effort is dealing with assholes"
You don't realise how much damage you did. I agree with gender neutral language in technical writing. Many others do as well. If you had dealt with this differently and not decided to become a self-aggrandizing pundit, then you would have probably shown that Joyent can deal with controversial matters maturely and civilly, play nicely with others, resolve conflict, and you'd have the high moral ground.
Now you just look like a bully, and I'd say you were the catalyst for the io.js fork. You also opened yourself up to your own past, which you also regret.
As I say - you've basically given us all a text-book case study into how not to manage an open source project.
P.S. FWIW, I upvoted you.