There is precedent for either roads or vehicles for choosing not to handle some conditions. In a driving rain storm you will find rest areas stuffed full of trucks and cars that picked that time to nap. In San Francisco Waymo first served some hours and not others, some areas and not others - some of these choices apparently related to fog and wet pavement. In Oregon, you will find roads open, but white-out-ed. Etc, etc. Nobody forces human vehicles to keep moving and most of the ones with some sense make choices. Which are available also to automated vehicles. - Sure it should be expected of the vehicle to find a safer place to move itself than right in the middle of the lane, like I point out in another response here.