Not showing routable children pages when a parent is set non-routable in pages blueprint form field

When you use the _pages_ blueprint form field in the admin, it doesn’t show children routable pages when their parent is set as non-routable.
It should be fine to have a non-routable parent page while keeping its children routable. Anyway, if you want to link to it using a _pages_ form field you are forced to set it as routable.