It’s sad that the USA is becoming one of these countries. But yes, that’s what I’m doing - travelling to free countries and avoiding the backwards ones.
IMO the USA is not becoming one of those countries and people are just fearmongering. But legally they can do it so it's better to take precautions anyway.
It also sounds like the guy was actively and openly trying to convince researchers to leave the US for France. May have even been the purpose of the trip.
Free speech is one thing, extending a visa to foreign individuals that are actively working against the country's interests is another. Few if any countries would grant visas knowing that intent.