Stephen,
You could open moodle/blocks/admin/block_admin.php and comment out the code around lines 119 to 125 like below. This doesn't actually remove this feature...it just removes the link from the course admin menu. You can still get to the student screen by entering the course and then replacing "view" in the browser address field with "student". I've removed several items in the course admin section on one of my sites like this...teachers don't know the capability exists, but I can manully access the features by entering the correct terms in the url....note, teachers could access this feature by entering the correct url as well, but unless someone shows them how to do it, most would never know the capability exists or how to do it.
Also please note, I'm a hacker not a programmer...no guarantees so use at your own risk .