I agree.
Even if all children responded to the consultation, when you have a generation who are still too young to really appreciate the fundamental differences between a male body and a female one, and who have had it drip fed to them from a very young age that they can choose whether to be a boy or a girl and that it is all a question of identity, I would expect a high proportion of them to respond to the effect that trans girls are girls and trans boys are boys because anything else would be transphobic. It would take an extraordinary level of critical thinking, independent thought and bravery, frankly, for a child to respond, "Actually, we girls have a right to our own toilets and changing rooms, I don't want to share these spaces with trans girls and I don't want to compete against them in sport either."
I don't think it would even occur to them that they had the right to say that.
In reality, however, I would not expect many non trans children to respond to the consultation because responding to government consultations is not something children would normally think to do, so the responses from children will pretty much all be from trans identifying kids and their "allies", egged on by adults.