I agree with your basic skepticism regarding President Trump's statements. We are far beyond 'it's just the flu, bro'. Unfortunately, most people fall into either the Orange Man Bad or the God Emperor Trump camp, so rational skepticism and independent consideration of available facts are going to remain minority views.

Since rational people understand their survival is their responsibility, we are required to consider how official actions will fall short, or wildly exceed, what is necessary and desirable in pandemic prevention and survival. Travel restrictions are like quarantining countries, and we should be doing this without regard to economic concerns for countries - at least - with known community transmission ongoing. Presently, unless we test every individual entering the country multiple times (testing is shown to work ~30% of the time), we cannot ascertain whether or not they are carriers. People can be infectious for a month prior to showing any symptoms, or perhaps even remain asymptomatic indefinitely, yet infectious, like Typhoid Mary.

Quarantine does work to prevent transmission of the infection. It reduces physical social interaction, which is the primary vector for the virus. Brutality as witnessed in China's imposition of quarantine in Wuhan reduces quarantine effectiveness, because it forces people to flee instead of enter quarantine. Other actions we can take as individuals can dramatically reduce transmission, and we should all begin doing them. Dr. James Lyons-Weiler says:

"Overall, if we all act as though we, and everyone we meet, is infected, and do not shake hands,hug or kiss, use the “Ebola elbow bump” to greet (in short, keep your fluids to yourself), don’tshare food or utensils, carry and use tissues, and throw them in the bin (as HMG suggests), wipedown all common public surfaces w/bleach wipes (door knobs, door handles, keypads, elevator buttons,bathroom fixtures, light switches) throughout the day, we can all work together tobring R0 down to below 1.0. And we should do these things anyway during flu season."

Lowering the R0 below 1 stops the spread of the virus.

Thanks!