the 9th was only ruling on whether the lower court's STAY, could stand....
by ruling it could stand until the actual case could have a trial, implies that there are reasons to believe, those suing have a good chance of winning in court, once the 'fat lady sings'.
HOWEVER, this appellate court was ONLY deciding whether the STAY could stay in place while the lower court hears the case in trial on whether it is or is not, constitutional....so Trump lost the part about rescinding the STAY, but not on the merits of the case yet.