The case wasn't dismissed because of the arbitration clause. Disney dropped the argument after they got severely lambasted in public over the absurdity of the defense. It was dismissed later by the plaintiff (so there was likely some settlement)

I don't think this is the last time we will see this argument. Disney has a lot of value in brand equity to protect so it made sense for them to back away, but a "bad guy" company that's already regarded with distrust will probably go all in on this in the future.