Non-binary is not a gender
While binary evokes a gender-duopoly, non-binary is really not about gender at all.
When we are actually thinking about our work, and that is in the minutae of the tasks, how much do we actually think about our gender? I doubt anyone has ever thought while programming, As a man, how do I write a program to perform a sieve sort?
That is the essence of non-binary thinking, which is about not thinking about gender when it is not relevant at all. The real point here is that for the great majority that most of us do during the day, gender is not part of our thinking. It is only when we are idle we may turn to our idea of our gender and what it means to us.
If that is the case, then why the big focus on gender, and what forms it might take? That is more to do with preserving societal roles than about what actually people do with their thinking time. It is important to many who want to control our societies that gender be a principal decider of our key relationships, just because embedding that thinking in societies fosters their continued status and privilege as part of that gender. Such people do not want the complications that come with having more than two, let alone that it can be a personal choice.
Thus the idea of trans people threatens the whole investment in the simplicity of fixed genders and thus fixed roles, leading to predictable, and exploitable, outcomes. Having gender choice is a consumer option that undermines the exploitable order of things. 1.7% of people are not born as only one gender, which undermines that basic premise, but when steps were taken in the past to make such people conform to one gender, often without them having any choice in that process, they have had to choose to play that gender role, which undermines the whole gender is not a persoanal choice spin.
Thus gender can very much be a choice about what role we want to play in life, but it is not mandatory, so we can also choose to leave it out of consideration altogether for what we think about the majority of our time. If other are demanding adherence to gender roles, look to their motives, because they will not be concerned about welfare at all, but how it challenges their investment in the continuation of their own choices of their own roles. Do not be sidetracked by others' expectation of roles. They are always a personal choice, unless we acquiesce.
There are many situations where ideas of gender may be relevant, but we are often asked to specify a gender even though the real purpose of the question is not about our preferences at all. Such a situation is in medical examinations, where the question is often asked of the patient, but what really needs to happen is the practitioner needs to make their own assessment of the patient's characteristics. For this, there are the words
These are at the discretion of the practitioner and not the patient. The terms may apply to different parts of the same person, and so the practitioner only needs to refer to the parts of the anatomy they are interested in. These situations highlight why making gender some ultimate criteria for judging ourselves just creates extra complications unrelated to the situation at hand.
As for sports, that 1.7% has already created problems, and trying to shoehorn everything into two genders for some convenience of deciding who the elites are is the real problem. Many sports rank competitors by other criteria than gender, such as weight, so perhaps there are also other criteria that can be used to classify people more fairly. Then it would not matter if they were trans or not, but what performance category they are in.
Having a term composed of a negative is perhaps what creates some confusion for many, so it might be that we will come to another term that more correctly reflects the positive and eclectic nature of the thinking state we want to be in.