To me, at least, shooting a peep with the rear sight just isn't as good as shooting it without the rear sight. Even if you remove the elevator from the rear sight, it takes an extra moment or two to pick up the correct sight picture with the extra clutter.
But with practice a guy can shoot fine and fast with the rear sight there.
My person recommendation would be to remove the rear sight and replace with a blank. Wrap the rear sight and elevator up in some wax paper or a ziplock and put it into the stock bolt hole under the buttplate. Even if they forget it's there, at least it will never get lost.
Glad to help him out. Hope they keep hunting that gun for another 90 years.