My guess is that they are simply suffering from analysis paralysis.
The CDC is afraid to make a decision that could result in another Diamond Princess incident. They might be more afraid of having to house and treat foreign passengers on American soil, unless they open up cruising from American ports to American citizens only.
They are more afraid of the press over such a case, rather than laying the expectation that IF it happens they are ready to handle it.
Either that, or they believe Obama's warning to never underestimate Biden's ability to eff things up.
-PJ
Well if brave Americans hadnt risked the Indians the West would not be populated to this day...
Oh dear no California...that state would still be Spanish/Mexican...and NM, AZ, and TX...
America would still be only 13 colonies...