@Harassedevictee
Unlike most, if not all of us on this thread I have not spoken to Ash nor read all the evidence. The judge has.
The judge was clear about what Ash did and did not understand. What the judge and we disagree on is not anything specific to Ash that the judge knows and we don't. It's whether that level of understanding in a 16 year old is sufficient to make that decision (or set of decisions) and then be expected to live with consequences of getting it wrong. The judge thinks yes. We think no.
At 16 Ash appears to have a better understanding of reality than 27 year old Freddie.
16 year olds change fast. 16 year olds can't visualise themselves as older people with very different priorities from ones they have now. They think short term. They make decisions now and assume later consequences will take care of themselves or that they will manage somehow but with only the haziest and least realistic ideas of how. The judge cannot have determined that Ash is the exception because there is no way for the judge (or anyone) to know that, there is no special secret information or insight.
A 16 year old may know all the facts that you stated but cannot visualise the impact of those facts in future on Ash's body, mind and relationships. Ash's suggestion that their sister might donate eggs only demonstrates how little Ash truly understands about adult bodies, adult emotions and adult relationships.
It's not possible to predict what they a 16 year old will want even in a few years' time. There is no way to predict whether a 16 year old will want to breast feed in their twenties or thirties. All you can know for sure is that they are more likely to change their mind about it than a 30 year old - but even a 30 year old can change their mind. You can choose not to breast feed, or to stop breast feeding if you hate it, but you can't grow new breasts.
The most common direction of travel with age is from "not wanting children" to "wanting children" and usually towards "wanting my own children". The other way round is much rarer. Ash already wants to have children at some point, or that conversation with Ash's sister would not have happened. Sterilising a healthy youngster who wants (or knows they might want might want) to have children later on is not ethical.
Children have - or should have - a right to an open future. Not to have to live with decisions whose full effects they couldn't be expected to conceptualise. Waiting even a couple of years to formal adulthood makes it just that bit safer.
I don't know enough about Australia to know if this judge is an extremist or has typical views for typical for the area they live in. Or something in between.