I dont think the goal of travel restrictions is to keep the virus out of an area, just to slow its spread. Slowing it even a week or two could buy time for preparation, to processes and plans nailed down, how to handle outbreaks so you dont end up with sick first responders and healthcare workers.
Any slowing helps the healthcare systems.
We bought some time when we stopped planes flying from Wuhan but needed to keep expanding it to endemic areas. Its not something you can do halfway if you want it to work.
Local news is reporting #COVID19 quarantine trailers are being set up in addition to the purchase of a motel.