That doesn't mean that all 500,000 are currently out of the country and unable to return.
Seems like excessive hyperbole to me.
"Give me your tired, your poor, Your huddled masses yearning to breathe free, The wretched refuse of your teeming shore. Send these, the homeless, tempest-tossed to me, I lift my lamp beside the golden door!"
Suggested alternate: "Executive Order Could Block 500K US Residents From Returning to US From Trips"
That doesn't mean that all 500,000 are currently out of the country and unable to return.
Seems like excessive hyperbole to me.