It took the better part of a year to strike them down the first time. So he needs what, 4 more justifications to keep them up through his whole term?
As far as I know the only way to stop him from doing that would be to remove him from office (there will never be 67 senators willing to convict a president in our 2-party system).
Absolutely. The courts are too slow to be an effective safeguard, not that that's their only issue though.