I think the article plays a little fast and loose to make a point. Not sure, but I'd always believed / assumed that the confusion around this topic was based on confusing terminology around three ideas: physical gender, gender identity, and attraction.
Personally, I have no idea what to do about or with physical gender, which seems to be what you're replying to. I apologize if my reply is off topic.
This article mainly seems to deal with the gender identity and attraction layers (attraction only in so far as the many gender definitions).
My concern with the proliferation of gender identities is roughly in line with the article. Feminism and early movements were inclusive and intended to dispel the idea that men and women were mutually exclusive properties. Instead, I believe, they were intended to show that there was a spectrum between men and women that everyone inhabited. So currently I'm on the same page as the article.
But my concern isn't the logical aspect of non-binary (though that is where the article is strongest) so much as the intention. By listing and itemizing identity you've changed the intent. As a 30 something white straight male I can't possibly understand the stigma, so maybe having your own *gender is preferable, but on the whole it feels divisive and weirdly clinical. That seems self-destructive; instead of making whatever you want to be normative you're trying to prove you're different.
I could probably type pages more, but like you I am not up to writing a rebuttal. At the very least I appreciate the reasonable tone of the article and hope the response to it isn't harsh. This really is one of the most important issues of our time and it feels hard to have an earnest discussion about the pros and cons of how to approach the issue.
In the end I think I agree with the conclusion... We shouldn't be categorizing every possible identity or attraction; we should be making it a more normative part of meeting people casually / romantically to have discussion about who they are and who they're attracted to / into. By throwing up divides we're short changing ourselves.