It may be hard for them to win because courts do defer and give discretion on immigration, and they'll definitely try to justify it with national security interests, which is a winning argument many times.
As I pointed out, green card holders have the same rights (sans voting) as the rest of us, including the right to travel. That's true for new green card holders who have not yet entered this country, as well, no matter where they come from. If I can travel to Somalia & come back, for example, they can too. It's always been that way until... Trump goes grandstanding.
It's all bullshit. There's absolutely no basis to believe that an Iraqi or an Iranian is any more dangerous than a Saudi or an Afghani. It's fantasy.