If your son works in health care and had COVID 19, I am not sure why he would even ask such a thing from you. I agree with your husband. Safer in separation. Your doctor would/should agree with the recommendation to live at separate residences while he recovers completely- no cough, no symptoms! and if he were to move back in, a place for him to change and disinfect his cellphone/ personal items and shoes prior to entering the home.