FYI, and to take another approach to methods for culling photos-
If you were to use Pick Flags, instead of Star Rating, there is a Menu command that can be very useful-
"Menu: Library > Refine Photos" [Ctrl+Alt+R]
This command 'demotes' the FLAG rating status of photos that are presently being seen in Grid view.
-Photos with a 'Pick' flag are demoted to 'Unflagged'. Flagged > Unflagged.
-Photos without a flag 'Unflagged' are demoted to 'Rejected'. Unflagged > Rejected.
Then you can delete (cull) all the 'Rejected' flagged photos with the one command [Ctrl+Delete].
So the method is- View a folder or collection of photos, Add a [P] Pick flag to all the photos you want to keep (faster with auto advance), [Refine Photos], [Ctrl+Delete].