That is not applicable here. The US Supreme Court has repeatedly asserted that freedom to travel in the US is a fundamental right like free speech; regulation of interstate commerce is prohibited from violating those rights. Suspension of that right requires a narrowly targeted and compelling government interest, blanket prohibitions are prohibited, and requires due process for affected individuals.

In other words, "you might have COVID-19" has the same authority granting power as "you might be a terrorist" or "you might be a child pornographer", which is to say, very little absent specific evidence.

I have zero faith in the current federal and supreme courts upholding those rights. Stare decisis is basically dead and a full third of the judiciary are federalists or federalist-adjacent.

Also, I think you drastically underestimate what can be legally done under the aegis of "you might be (insert undesirable class here)".