Top grade category name field appears useless

In the gradebook, when I edit the top category (the one named after the course), I see a field called "Category name", with "course grade category" in it. I can change this value, but it has no effect on the display of the category in any of the reports.

It seems that the top category name is overriden in the reports so that it shows the course name instead. The field should probably be disabled if this is the case.