Then lets extend it to pheasant hunting and varmint hunting too. If a poor fellow with limited vision wants to shoot a flying bird, then by God we should let him. At least a shotgun's range is more limited then a rifle.
It is not illegal to hunt in dense fog for upland game. However, common sense tells us not to. The fog hampers vision and thus makes shooting dangerous.
If, God forbid, the sight hampered shooter does accidentaly injure or kill another hunter with his shot, who will be held responsible?