Seems to me, that some low level glow from the display should be harmless. How else could one tray-process sheet film and use the timer anywhere nearby? So far I placed a ND filter over the display when tray or tank processing, but I never tested whether that was really necessary for my setup.However we could probably add a third "off" setting to the User Options display menu which already has a "dim / bright" setting. Would that be useful?
I think the 'total darkness' required for handling film is really a 'relative darkness', a 'relatively total darkness'.