Why should I believe this? They can shut down their servers, move their crypto to different wallets, and pop up again in a few weeks, right?
They know that they can and will be found, and are running scared. In general ransomware works because it takes a lot of resources to find the criminals behind it. And generally there's not enough resources to do this. But once it hits a level where it creates a widespread national problem, it becomes more of an act of war. Then you get people involved that aren't just law enforcement and have tools that aren't available to law enforcement with large budgets.