"The Fourth Amendment prohibits unreasonable search and seizure; it's eminently reasonable to expel people from a public health danger."
Clever. But isn't there also a bunch of stuff about warrants and probable cause and such legal details?
"The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."
The 4th Amendment died some time ago. NO was its 'official' funeral.
It's hornbook law that in an emergancy ("exigent circumstances"), a warrant is not required because the search and seizure is reasonable. That's why cops can burst in through a door to preserve life and limb if they have probable cause to believe that this intervention will stop a crime in progress.