They didn't rule on it because it is out of scope of the matter before the court. The lower courts first have to make a ruling that can be appealed.

From the ruling:

> The conclusion that a Fourth Amendment search occurred does not resolve this case, because the Fourth Amendment prohibits only searches that are “unreasonable.” When law enforcement officials undertake a search to discover evidence of a crime, the reasonableness standard generally requires that they seek a warrant from “a neutral and detached magistrate,” Johnson v. United States, 333 U. S. 10, 14, who may issue a warrant only when “probable cause is properly established and the scope of the authorized search is set out with particularity,” Kentucky v. King, 563 U. S. 452, 459. The warrant issued here, as described earlier, was an uncommon, multi-step one, and the parties have contested the legality of each stage of the search process it authorized. The Fourth Circuit did not address the questions that unusual warrant raises. Because this is “a court of review, not of first view,” Cutter v. Wilkinson, 544 U. S. 709, 718, n. 7, the Court leaves it up to the Court of Appeals to decide whether, at each step of the search process, the warrant satisfied the Fourth Amendment’s requirements of particularity and probable cause