Those other absurd laws aren’t remotely relevant, hence the lack of acknowledgement. Many are irrelevant or very old. There is a large movement in the US that seeks to demonize trans people in sports, and this law isn’t that old, so in the current political climate there’s definitely a non-zero chance it gets acted upon.

And that the law allows you to correct your birth certificate does not mean that the law assumes your future to-be-corrected certificate is currently legally valid. I’m sure they’ll get it resolved eventually, but at that moment the school felt they had to apply the law.