What the author means is that the majority was divided; there was no opinion that carried 5 votes. The majority was made up of 3 separate opinions(Kennedy's opinion was joined only by Roberts and Alito; Scalia and Thomas concurred on a different ground; and Breyer concurred on a third ground).
I realize that now from reading other articles. This one didn't mention that fact or even give the information on how 6 of the justices voted.