I read on the dark web that there was an unauthorized small aircraft in the area that started dogging Trumps aircraft and would not identify themselves. So to make sure nobody became a Kamikaze hero, they landed.
I will say, that it is not out of the ordinary for there to be unauthorized aircraft in the air in the wide open expanses of the west. Many ranches have their own landing fields and airplanes are used for legitimate reasons. I have a friend in Alaska who uses their airplane like you do your car. They only notify an airport (regional) if they will be landing at it.
Locally, there are power generated paragliders (paramotoring) who never file a flight plan. One is a member of my area MAG. I think he said, the last time I chatted with him, that his average speed is around 30-35 MPH. Could he be a Kamikaze hero? Sure but probably only on a large aircrafts descent to land near a larger airport. The paramotorer would probably be noticed before the larger plane made their descent.