This is a very shitty ruling that denies basic mathematical fact: a graph of nodes contains data that simply isn't present in a lone node.
Edit: The difference actually springs from a qualitative difference in the search. In the case of a lone person, the government is seeking information about that person in a vacuum; in the case of hoovering up millions of records, they're explicitly looking for interconnections, which is different in kind than if they were looking at each record in isolation, and just happened to have millions. The FISC court is essentially misrepresenting the nature of the bulk search by pretending it's merely many copies of an individual search, rather than a different type of search, altogether.