You are correct; all the more reason for Trump to shop a judge, establish the court’s jurisdiction and maybe even obtain the rule BEFORE he issues the decree.
Perhaps that is what he is working on .... remember how he suggested after the last 9th court circus that he would work to prevent such judicial shopping in the future?
All Trump really needs is for 1 judge to simply say, “I have national jurisdiction on this issue and all cases from here forward must go through my court.”
That is what the dem judges do when they issue ‘nation-wide injunctions’.