Under ordinary circumstances you’re absolutely right, but these are extraordinary circumstances. Also, Michigan had 2,000 cases a day for a while, yesterday they were down to under 200, so something’s working.
People who have 2nd homes could potentially bring the disease to a place where it didn’t previously occur. It’s like spreading a new disease to an Amazon tribe that has no contact with the outside world - they don’t have vaccines or immunity to various diseases, just like people with COVID don’t have access to vaccines and there’s limited immunity, though antibody testing is giving us a better idea as to who would be.
In other words:
If I’m infected and go to my 2nd home in a town that doesn’t have any cases, wait in line at a convenience store for food that I forgot to bring, and spread it to the people there, suddenly I’m responsible for new cases spreading in that town. What other protections would the citizens of that town have? How would you hold me accountable for spreading disease and death there?