There is zero biological argument because you cannot make two categories based on sex which encompass everyone.
Example 1:
A cis woman with a genetic mutation which incrases her testosterone levels into the range of cis men. Should she be banned from female competitive sports?
Example 2:
A cis woman with XY gonadal dysgenesis. She has XY chromosomes but the Y chromosome is mutated and doesn't function as it should which causes a "female" phenotype. Should she be banned from female competitive sports?
Example 3:
A trans woman in the 95th percentile of men with regards to physical strength. She is in the 10th percentile of women after transitioning. Should she be banned from female competitive sports?
Example 4:
A trans woman with Klinefelter syndrome and XXY genes. She has naturally very low levels of testosterone and she doesn't require testosterone blockers after transitioning and taking estrogen. Even before transitioning she had less muscle mass, weaker bones and wider hips than the average man as a result of her low testosterone. Should she be banned from female competitive sports?
Example 5:
An African woman who would be in the 1st percentile of man if she were one, both in terms of physical attributes (size, muscle mass, heart size) and competitive results. Some "scientists" argue her race makes her less of a woman and more of a man. Should she be banned from female competitive sports?
There is zero risk of these people "replacing" cis women by the way. Yes, their performance may be greater than that of comparable cis women without any genetical mutations beyond a certajn point.
Yet risk is calculated as [severity] * [likelihood]. And due to the low likelihood stemming from their very low prevalence in the general population, there is no reason to ban them.
Women's sports is about representation of women. Trans women are part of that group, cis women with genetic mutations are part of that group, racial minorities are part of that group. You cannot exclude some women and claim this group is "fair" and representative.