Re: “ Pretty sure Presidential Executive Order is the law”, nope
True, but Congress has passed many laws granting the Executive powers it can exercise with the force of law, because the law says so. These funding bills they're always passing (remember the One Bloated Butterface Bill?) or not passing (see the current shutdown) are in no small part made up of money stuffed down the Executive's blouse for this or that purpose, thus making the execution (aha! see?) of those tasks by order of the President a matter of law.
Of course, over the centuries we've increasingly granted the President more and more latitude in interpreting those legally-obligated tasks and in deciding how exactly to go about them.
Or NOT go about them, because the argument has been made, and.came up again during Obama's first term, that if any part of the office's obligations under the law are likely to be deemed Unconstitutional by the Supremes, then the President has an obligation NOT to carry out that task.
Because when a law is struck down as Unconstitutional, it doesn't become invalid only at that point. A law struck down by the highest court was NEVER valid to begin with, and any actions that the Federal government took in implementing that law were unlawful acts
(Not that anyone involved would be likely face criminal charges. The government's actions are unlawful, not the actions of any civil servants obeying the law as it was understood at the time. You need some seriously exceptional circumstances, like the Nuremberg trials, for civil servants to go down because they followed the law and did the job as defined to them.)
...Getting back on track, tho: Problem is, we all know THIS Supreme Court isn't going to be slapping any of Trump's executive powers out of his hand -- real OR imaginary.