Safety by private agreement is a cartel
When the four largest firms in a market agree on how good the product may get, the burden is on them to show why this is not the oldest trick in commerce.
Every cartel in the history of commerce has described itself as responsible restraint. Railways agreed on rates to prevent ruinous competition. Airlines fixed fares for the safety of the industry. In each case the explanation was sincere, widely believed, and worth a fortune to the people offering it.
Notice which firms are proposing the pace. They are the four with the largest models, the deepest capital and the most to lose from a competitor arriving with something better and cheaper. A ceiling on capability is a moat for whoever is already at the top of it.
If the danger is real, the remedy is public and it already exists: legislate, license, require evaluations, impose liability. All of that is legitimate, reviewable and applies to every entrant equally. What is not legitimate is four companies deciding among themselves what the market may be offered and calling the result governance.
The test is who is in the room. A rule made by Congress binds the firm that has not been founded yet. A gentleman's agreement among incumbents binds nobody except by their consent, and is abandoned the moment one of them sees an advantage in abandoning it.
The labs cannot have this both ways. If the pacing commitment is real enough to restrain output, it is real enough to be an agreement, and agreements between rivals about output are the plainest thing competition law prohibits. If it is not real, it was public relations, and the answer is to stop pretending it was safety.