As people express a sense of panic over the corona virus, and are staying at home, this is a perfect time for the administration to oust subversives in the US: people who oppose the US government, and have expressed the desire to overthrow it. There are drug gang members in every state, and in every county of every state. Would they create disruptions if their operations were interrupted? Quite possibly. Are there foreign elements involved in human trafficking that would be upset if the border is closed? Quite possibly. Cleaning this all up prior to border closure will be a sizeable operation. A good place to find subversives, one might guess, is in the sanctuary cities.
What about carriers of the corona virus that come into the country? We are learning that airport screening is impossible. There is no way to stop infectious diseases coming into the country that way. To stop the spread of disease from travelers, one must close off entry.
Tom Hanks, may be contacting Elon Musk for a flight out of this world. Stay tuned for that one.