There are only a handful of trans women who compete in school sports. We should not be wasting so much of our time debating trans women in sports when there are only a few trans women athletes in sports.
These women are not a threat to "biological women." Any predatory man who would seek to excel in women's sports would not participate in women's sports because it is a lose-lose situation for a man in our culture. The man either "got beat by a girl" or "beat a girl." Only women who are truly women (including trans women) will compete in women's sports due to the stigma of a man playing sports against a woman.
In sports, genetics give people unfair advantages. A 6'3" person is likely going to be a better basketball player than a 5'3" person. Currently, I do not think there is enough research on trans athletes and "biologically female" athletes to support that trans women have an unfair advantage, but even if they do have an unfair advantage, it is not dissimilar to all of the other unfair advantages inherent in sports. Studies on women athletes are not as plentiful as studies on male athletes, and many women are held back due to sports-induced eating disorders. When we truly have good data on female athletes and women are supported to train and fuel appropriately, we may see women's capabilities in sports increase. We need more studies on female and trans athletes!
Furthermore, the trans-ban would hurt all women. It would require women to undergo degrading testing to prove they are women and many women would be subject to accusations that they are not "true" women or are "too masculine" to compete.