can you try to keep away from him in the house, depending on how big it is, do you have 2 loos.
remind everyone to put the lid down before flushing, i read something yesterday about the virus remaining in faeces for many days after symptoms have subsided, and toilets create aerosol effect which spreads the virus in droplets.
i think you have to take whatever measure you can to keep yourself as safe as poss. wipe everything, shopping, handles.
there are many phone-ins on radio, could you ring one when he is there and ask the expert to explain to him.