"They are too young to know what they want!"
You know, this first argument sounds like the very reason we don't let kids have sex: because they are too young to understand it.
The thing is, when something happens and is forced on someone too young to understand, generally, well, that's the reason pedophilia is special among evil acts.
So when we have no choice but for something to happen, when people express at that age a desire for a specific thing to happen, and when not only is it in our power to fulfill some of that of which we do let happen them but also even have power to delay this onset so that they may consider... And then we force upon them an immediate and irreversible outcome that is none of those things, but exactly what they do not want...
Well, that carries that same burden as "pedophilia".
Congratulations, if this describes you, you want to rape a child with an unwanted puberty. I did a mental exercise to compare it to an unwanted rape pregnancy but they're both just completely fucked up.
"They will be sterilized!"
I could give a shit less of a fuck. They can adopt if they want a kid. It is far from certain, and as some have noted, we don't need more kids. As technology progresses this may not even be a concern in the long term.
Regardless, the people who make these arguments remind me of the doctors I hear stories bout on /r/childfree who patronize (mostly women) and either expect their husband's OK, second guesses their convictions, or otherwise flat out denies them. My visceral reaction when I see this is "my body, my choice; if you think my body, your choice, then your body my choice," I kIck them in the gonads until they break. Of course I wouldn't, but I would like to. Instead they would be getting a complaint filed with the state medical board, along with whatever other malignancy I can bring into the life of a gatekeeper on reproductive self determination.
@TomC will obviously agree with me that this is a spurious argument as well, I am sure, because of how they have argued we have enough people already.
"There will be false positives!"
That's why the blockers for those in identifiably questionable circumstances, so that their situation may be parsed.
In all honesty I would support unilateral youth choice to take blockers, without parental permission or consultation, universally.
Anything else is, well, we end up right back at the first whinge.
And conveniently, this solves the problem of testosterone exposure in leagues specifically formed because testosterone exposure creates a different competitive class