Executive Order 13769 (the so-called "Muslim Ban") actually was effective immediately, resulting in a similar race to the airport during its chaotic implementation. Hundreds of people with previously lawful immigration status were denied entry or detained, including dozens with green cards despite those being excluded by the EO.

In any case this new order was not ambiguous. It plainly said the restriction was on "entry", not the issuance of new visas. Nobody reading the text of the order claimed otherwise. The Trump administration just changed their position, in informal guidance rather than a formal executive order but with similar practical and legal effect.

Anyone who returned early was effectively hedging, paying the airline change fee and some inconvenience to avoid a potential $100k fee or worse, with downsides including job loss--potentially leading to forced repatriation--if your employer doesn't pay, and indefinite detention under harsh conditions. That hedge currently seems likely to expire worthless; but with such an imbalanced payoff, are you really saying you wouldn't have paid it yourself?