In Moyle v. United States, Justices Alito, Thomas, and Gorsuch would have maintained the stay. Indeed, they signaled that they would rule for Idaho on the merits. But they were in dissent. And at times, it was a cantankerous dissent. (Justice Gorsuch did not join Part III of the dissent, for reasons he did not explain.)
Justice Alito provides a peek behind the curtain, and suggests the stay was granted in January based on the "likelihood of success on the merits."
Recognizing the flaws in the Government's theory and Idaho's "strong" likelihood of success, this Court stayed the preliminary injunction pending appeal on January 5. And, wisely or not, the Court also took the unusual step of granting certiorari before Idaho's appeal was heard by the Ninth Circuit. See this Court's Rule 11. Now the Court dismisses the writ and, what is worse, vacates the stay.