One point should be clear from the Supreme Court's per curiam decision in Trump v. International Refugee Assistance Project: references to campaign statements by presidential candidate Trump urging a halt in Muslim immigration to the United States will not be persuasive in court.  At issue, according to the opinion, is U.S. national security, and the federal government is uniquely situated to decide the matter.

The following statement from the opinion seems to provide the essence of the opinion's rationale:

An American individual or entity that has a bona fide relationship with a particular person seeking to enter the country as a refugee can legitimately claim concrete hardship if that person is excluded. As to these individuals and entities, we do not disturb the injunction. But when it comes to refugees who lack any such connection to the United States, for the reasons we have set out, the balance tips in favor of the Government's compelling need to provide for the Nation's security. 

This opinion does not rule on the merits.  Rather, in overturning lower-court stays on the travel ban, the Supreme Court, with only two dissents – from Justices Ruth Bader Ginsburg and Sonia Sotomayor – signaled that in balancing the equities, will defer to the government with respect to travel bans affecting individuals lacking any ties to the U.S. 

But in a concurring opinion, Justice Thomas, joined by Justices Samuel Alito and Neil Gorsuch, believes that the opinion "will invite a flood of litigation" from individuals contending that they have "bona fide" ties to the U.S.  Here is the gist of the caveat from Justice Clarence Thomas:

[I] fear that the Court's remedy will prove unworkable. Today's compromise will burden executive officials with the task of deciding – on peril of contempt – whether individuals from the six affected nations who wish to enter the United States have a sufficient connection to a person or entity in this country[.] ... The compromise also will invite a flood of litigation until this case is finally resolved on the merits, as parties and courts struggle to determine what exactly constitutes a "bona fide relationship" [and] who precisely has a "credible claim" to that relationship[.] ... And litigation of the factual and legal issues that are likely to arise will presumably be directed to the two District Courts whose initial orders in these cases this Court has now – unanimously – found sufficiently questionable to be stayed as to the vast majority of the people potentially affected. 

The opinion offers the hope that lower federal courts will stop using political animus against President Trump as a factor in their decisions and, instead, focus on the merits of the matter – in the case of the travel ban, U.S. national security.