Testable hypotheses are at the core of the scientific method, yes. But that's not just limited to the actual testing of hypotheses. All the work that goes into formulating hypotheses is also explicitly part of the scientific method.
Worth noting, too, that the paper outlines several possible experiments. It also specifically mentions some relative shortcomings of the model, and lists existing observations that they haven't tried to reconcile with it yet.
Worth noting, too, that the paper outlines several possible experiments. It also specifically mentions some relative shortcomings of the model, and lists existing observations that they haven't tried to reconcile with it yet.