Many parents worry about their kids worry about their children through their twenties, thirties, forties... doesn't change their right to information or their adult child's right to privacy.
My not having the right to my autistic 20 year old's academic information doesn't mean I think he should be left to sink or swim. I can support him with the information he chooses to give me. The thing is at this point, the decision on maintaining the relationship is on both people, not one-sided, not enforced by anyone. It's based largely on the relationship built up so far.
My son specifically chose a course at a place with a lot of additional wellbeing support. He's on a sponsored course - his contract states that if he fails out or is removed for other reasons, he can owe the sponsor what he's been paid for tuition and bursary no matter what he's paid - the sponsor still had to request he fill out paperwork to give them the ability to get relevant academic or other personal information on him, they don't have an automatic right to it just because they're paying. That can decide not to sponsor without it, just as parents can set whatever rules they want with their money.
The studies on brain development have, like a lot of science, been badly reported in the press. There is nothing magical about 25. What we know from these studies is that the brain never stops developing, that the 'full development' of the final significant pruning and connection varies depending on a lot of factors, with suggesting the window may be as wide as 19/20 to 28, maybe wider (I've seen 16 to 30, but not seen the studies on those numbers). We can't determine when adults get the right to privacy based on something like that. Some risks are part of life.
At 18, I immigrated to a different country and got married, even with what we would now call a neurodiverse condition. My parents were in the middle of a nasty post-divorce legal situation and my father demanded information on my location that a few people in my maternal family knew. I think it's BS that he was given my personal information and it put me and a few years after that my kids at risk - part of why I immigrated was my paternal family are part of an American evangelical group that thinks because I was baptised as a child, that my children are their property. I had to get British police involved after my location was given to my father due to stalking from members of the group including being sent photos of them in front of the uni I was at. Them being 'concerned' or my being under 25 and having disabilities doesn't change that I should have had the right to privacy and to handle the risks of my own adult choices.