I don't think so. The rape case really just acts as a vessel to provide standing to litigate the larger question of the reservation.
Without the rape case they wouldn't have had a reason to challenge the questions about the res but now that the Supreme Court has resolved the larger question it's applicable across the board.
It could have just as easily been a case about shoplifting or murder or anything else. In fact, last term there was a case similar to this that was about a murder, where the defendant was sentenced to death by the state and they argued that the state didn't have jurisdiction. Gorsuch heard the appeal in the circuit court so recused himself from the SCOTUS case and the belief it was deadlocked 4-4, so they took this case and made the ruling with a full nine Justices.