I mean, he is right that they can and should unilaterally slow down, but doesn't it also make sense for the government to create the regulations that will make this easier to do in a trustless way?

The whole point of the Pacing the Frontier letter was that employees at both OpenAI and Anthropic are extremely aware of the risks but realize that they are locked in a competitive battle for survival between 2 companies that don't trust each other enough to voluntarily pause, while any sort of coordination out in the open might be against antitrust laws.