Unfortunately, yes. It's a shame to see your comment currently at the bottom, since it's the point I wanted to make.

I think the example of the Norwegian tax system was a good one, because it demonstrates the article's point without any risk of discrimination. But the earlier example of Gender is a terrible one. Gender is more than just whether you have dangly bits hanging off your pelvis, it's also a very critical part of a person's core identity, and there are a lot of different variations. Lumping everything other than cis-gendered male/female into "its complicated" is a great way to make anyone who doesn't fit into the gender binary feel like they don't belong.

Perhaps a more compelling example would be race. I know there's a fairly standard set of racial categories used when asked to self-report race (e.g. in those optional questions you can fill out when doing various standardized tests), which are fairly broad, and I'm pretty sure the last one is "Other". But at least with race, nobody feels like their racial identity is not recognized as legitimate by a large percentage of the world population (which is a serious problem that non-cisgendered or non-gender-binary people have). But even here, imagine if the test just said "White, Black, or It's Complicated". It should be easy to imagine that a lot of people would be pretty outraged over that.

All that said, if you capture the main categories, and then have a free-form "Other" that people can fill in the details, that's similar in spirit to "It's Complicated" but a lot more palatable. Heck, depending on why you're asking the question, you might not even need to save the answer to Other (e.g. if you're only ever looking at data in aggregate, although even then you might want to pull out keywords from Other in order to report more groupings than the form offers), assuming the people filling in the form have no way of knowing whether you're keeping that data or not. So in the backend you might still have the equivalent of "It's Complicated". But how you present that to the user is important.

---

Edited to add: Looking back at this, I realize that it looks like I'm just talking about whether the user feels fairly represented, which is related to but not the same thing as whether the form actually discriminates against minorities. So on that note, I just want to emphasize the importance of picking an appropriate set of main categories, even if you have an Other, such that very few people should ever resort to using the Other, and those that do should not end up getting unfair treatment as a result. For example, if policy is made based on the demographics of a particular set of people, that policy needs to account for anyone who doesn't fit into the standard groupings. If you just have e.g. "Male, Female, It's Complicated", policy is almost certainly going to be made based on the standard gender binary, without accounting for anyone who doesn't fit.

And on a related note to that, it's not even just the person filling out the form who might feel unfairly represented by a poor choice of categories. Anyone else who does fit into those categories is going to see the categories as a reinforcing of their worldview, i.e. anyone who sees "Male or Female" as a set of gender choices will just be reinforcing the incorrect idea that everyone fits into the gender binary, and this helps cause discrimination.