Intersex are not 1% of the population. That figure comes from a study that included women with Turner Syndrome and PCOS, as well as men with Klinefelter Syndrome as intersex. Even a layperson would have zero trouble classifying the sex of said people if they saw their body.

Intersex as defined by genuine ambiguity of someone's sex is around 0.02% of the population: https://en.wikipedia.org/wiki/Intersex

> Leonard Sax, in response to Fausto-Sterling, estimated that the prevalence of intersex was about 0.018% of the world's population,[4] discounting several conditions included in Fausto-Sterling's estimate that included LOCAH, Klinefelter syndrome (47,XXY), Turner syndrome (45,X), the chromosomal variants of 47,XYY and 47,XXX, and vaginal agenesis. Sax reasons that in these conditions chromosomal sex is consistent with phenotypic sex and phenotype is classifiable as either male or female.[4]

So still like one or two orders of magnitude more common than trans athletes?