The Constitutionality is not in question, the question before the Court is whether the policy can lapse. There is no activism here.Is the policy constitutional? That's all they need to decide on. They don't make policy. "Stability" is not their concern. It's up to the lawmakers to do that.
The dems thought RvW was 'stable' after 50 years but SCOTUS thought differently. They did not create a policy, they just struck a un-constitutional ruling down and sent it back to the states.
As to RvW, the Constitutionality was always in question and now settled. Had the Court flip-flopped dozens of times since it's inception based on the politics of the day, it would be activism.