The standing “problem” will only be a problem for Justice Roberts and those other three.
I don't think it will take much to convince one of the remaining justices to take that door in the misguided hope that by sidestepping their duty to the Constitution at this time of national crisis they are saving the court.
There are five justices on the Supreme Court who must make the profoundest and most moral decision of their lives. If they behave as judges we may keep a constitutional republic. If they dance out the door they will have forfeited more than their reputations writ in the history books, they will have to conduct a very serious litigation with the ultimate judge.
President Trump has intervened(joined the case). He does not have standing?