Because it can't and it's a publicity stunt. It achieves three goals:

1) Underscores to the general public that the models are amazingly powerful and if you're not using them, your competitors will out-innovate you,

2) Sends the message to regulators that they don't need to do anything because the companies are diligent to prevent harm,

3) Sends the message to regulators that they sure should be regulating "open-source" models, because these hippies are not doing rigorous safety testing.

Both Anthropic and OpenAI have been playing that game for years.