You say you disagree, but even the parent suggests as much: "But it does mean that, for the first while at least,"

That's what I take their meaning as. That after you commit a crime, you have to prove yourself again, and that takes time. It's why you suggest 30s, and not 18. For a while after their crime, it would make sense to exclude someone.

On top of that, why so late? Why are you forcing your view that 30s is the earliest someone can trust someone again? Why not 18? Why can't a citizen decide to trust someone earlier than some arbitrary number?