i can acknowledge that a large percentage of trans kids will change their mind, but i don't think that's a good reason to stop them. when i was a kid, i planned to transition when i was older because i knew my family wouldn't support it; it was something that required a long-term strategy, and i didn't really get it in place until i was almost 30. yet, i also wanted to be a neurosurgeon when i was 10. i wanted to be a school teacher in my late teens, and regret the time i wasted studying math for that purpose; going to university to become a teacher was a huge mistake and an utter waste of time. we don't have laws preventing people from making mistakes, in general. it's ironic that these arguments are coming from self-identified libertarians, because it's actually nanny-state despotism to write laws to stop people from making mistakes. conversely, i wish i had talked to somebody about transitioning younger, because not transitioning (by putting it off) was also a mistake.
it seems like enlightened despotism to stop kids from making mistakes, until you realize it's arbitrary. transitioning young might be a mistake; waiting might be a mistake. going to school might be a mistake, or dropping out might be a mistake. getting married or dating whatever kid or a million other things might be mistakes. that's how kids learn, you have to let them make their own mistakes. on second glance, the truth asserts itself: it's authoritarian totalitarianism.
it's up to adults to provide information and support to kids to help them make the decisions they truly want, not to make decisions for them. adults should never make decisions for children, they should only act as support structures to allow the children to make decisions for themselves.