My money is on it being just another manufactured controversy. The majority court leaked it to generate "outrage" among the media/legal types while giving the political fallout several more months to simmer down before the midterms - giving time for another "outrage" to be generated for those with a short attention span.
It's possible, but it would be an incredibly short-sighted approach that would doom the career of the culprit.
The problem with the leak is that it destroys collegiality. The way the Court has always done things in the past has been hidden from public view. This permits open and frank discussion of what people actually think (via draft opinion circulation), before a final product makes it out into the world for consumption. Often times, the final opinion has been heavily revised in order to keep votes on board, and at times the majority opinion writer functionally changes (usually via concurrences, but occasionally through reassignment).
Once the first draft opinion leaks, that's no longer possible because everyone has to take into the account the possibility of a future leak. People have to start voting and writing draft opinions tactically, for fear of a leak which affects the political process outside the Court in undesirable ways.
The only rational reason to burn all of that would be if someone had cause to believe that Kavanaugh is wishy-washy, and can be moved from voting with Alito to a concurrence if there's a firestorm of public criticism. The way you get to him is through his love of having hot young female law clerks around, and making him realize that the flow of those is going to dry up if he supports this draft. My guess is that somebody in the chambers of either the three liberal justices or Roberts' chambers talked to somebody in Kavanaugh's chambers, and realized that Kavanaugh doesn't understand what's at stake for him.
We can figure out the culprit through what happens when Roberts investigates. If it gets blamed on one of the liberal justice's clerks or staffers, they're probably to blame. If it gets blamed on a hack, this came out of Roberts' chambers and he decided that broad-based public perception of the court's legitimacy was more important than collegiality. The former has always been his priority #1.