Spotted this while testing the other privacy changes. Here is a relatively plausible scenario:

1. My courses set to be a hidden user field (because you don't want students seeing which courses other students are in)
2. Using a Parent role.
3. You do want parents to be able to see all the hidden profile fields (so they can see all the information stored about their children - but also because otherwise they have no way to get from .../user/view.php?id=3 to .../user/view.php?id=3&course=2 to see their child's activity in a particular course).

Instead of a new capability, it may be better to re-use the existing moodle/course:viewhiddenuserfields.