Life isn't fair. But high school competition should try to be. Many of us have some sort of born/congenital condition that we have to live or deal with. I was born with only one kidney and didn't find out until a fluke thing halfway through high school. I was told that I should no longer play football because of it. So I stopped playing. I didn't ask for a special no tackle clause. Kids with congenital heart conditions can't participate in competitive sports. They don't ask for special permission and conditions to play.
Transgender issues are no different to me. It's not a judgement thing. Born one way, compete one way. Born the other, compete the other. Don't like it, tough luck. We all have problems. At least you live in a country that can provide you health and medical means to manage it.
I'm fairly liberal in my views but this is just one topic that grinds my gears. Males have significant physical biological advantages over females that aren't necessarily reversible with the gender therapy. Sports are an optional thing. Don't like the rules, don't sign up. Let everyone else try and have a fair and fun competition.
I think this is a valid argument. Being born trans could be legitimately be seen in the same category as being born with a disability (certainly if one embraces 'the social model' of disability). Anyone who has to live with a condition like yours just has to accept they are going to be at a huge disadvantage in competitive sports (I've known a couple of people who were born with extra kidneys, oddly enough - which wasn't a benefit, as it turned out, seemed to mean a lifetime of repeated kidney problems).
But with the crucial priviso that it _is_ about 'fun' and not taken too seriously, and people stop according excessive rewards of money and status to those able to compete. It's because it's not, in reality, usually about 'fun', but rather about money and the pursuit of status, that these problems arise. And school-level sport is strongly affected by the (mostly pretty corrupt) money-making industry that is professional sport. It's highly questionable whether the former would exist in the same form if not for the latter.
But arguing against organised competitive sport is like arguing against organised religion. Almost certainly futile. But I remain a Richard Dawkins when it comes to sport. The way it's presented at the moment actively _discourages_ a huge proportion of children (and maybe even the adult population, certainly insofar as they continue habits acquired in childhood) from being physically active (which is, in my opinion, the thing that really matters).
Edit - I mean, I can already here someone arguing that it's also not a level-playing-field for academic subjects, that some might just be disadvantaged in competing over being good at maths or language skills, say.
But the crucial difference is there the subject doesn't exist purely for the purpose of creating completion, those disciplines have an independent existence because they serve a purpose outside themselves. Those skills achieve useful results. The compeition is a side-effect and arguably unavoidable consequence. And that makes a big difference, because it means people can view the competitive aspects in a rational way, including making rational decisions about how to govern that competition, because it can always be balanced against the value of the external results of the activity.