NB is being confused here with GNC.
To say that the warrior was nonbinary would imply that they identified as neither a man nor a woman.
Whereas all we actually have evidence for is that the person was gender-nonconformant (or rather, gender-stereotype-nonconforming). Whether we even have evidence for that would depend on whether we have enough evidence to say confidently how the "genders" typically behaved in that place and time.
But as the person had a DSD (diffeence of sexual development) this raises a second issue. Such people are nowadays said to be "intersex" (in between the sexes). (This is not really true, as Klinefelter's is clearly a male DSD, but...) If this is the case then if this person was NB then they were also non-trans, since clearly their gender identity would have mirrored their physical sex. Nowadays NB and intersex are completely different things - I haven't seen evidence that intersex people are more likely to be NB, yet in this article IS & NB come close to being conflated.