Except that interpretation ends up being circular in a way. They don’t have the characteristic, but one day they will belong to a sex that is associated with producing them, even if they personally never do. The wording is very weird because they think they are sidestepping chromosomal and hormonal anomalies, but end up in either taking them literally at their word (no one is any gender) or applying some looser interpretation that becomes flexible since “belonging to a sex” is then not tethered to any objective fact since the timeframe is then up for grabs.
For example, they could have said “if the sperm contributed a y chromosome, then male, else female”. But they probably were thinking of things like Morris, Kleinfelter, and Swyer and wanted to have wording flexible enough to account for those. But it results in enough ambiguity to allow for things.
But even in the future the language is a bit wonky. If you are sterile for some reason, does that mean you have no gender? Well, guess it does say that you don’t have to actually produce those cells, you just have to “belong to the sex that produces the cells”. Ok, but then it technically avoids defining what “belonging to the sex means”, except to say that determination is done at conception, which opens the question to whether they consider a Morris Syndrome person to be a man? Or do they consider that person to have “belonging to the sex that produces larger reproductive cells” even if they, personally do not. Some people can go many many years without knowing they don’t have ovaries.
It’s strangely awkward and even more convoluted for their attempt to avoid saying it is the y chromosone.