You're still avoiding the central issue. We're talking about consent. You're also assuming that parents will always make the correct and best informed decision for their child. I'm sure they want to do this, but they're hardly going to be objective.
You want a simple answer where there isn't one. Children don't always make sensible decisions. They don't always know what they want. To pretend that it's anti trans to say this is ridiculous. We have all kinds of laws in place to protect children from others and from themselves. Is this law the best solution? I honestly don't know. But it's not hard to understand the thought process and it's childish to always paint disagreement as bigotry.