"when will the DOJ arrest Altman for misuse of computers"
never, and nor should they.
The US CFAA (U.S. Computer Fraud and Abuse Act) requires intent. There is no evidence that this was a deliberate act.
Under the doctrine of vicarious liability, you can sue a company for the actions of its employees but, in this case, OpenAI employees did not intend or order the attack.
Hacking law does not include provisions for accidental hacking. Legally there is no such thing.
It's why major tech corporations are not liable if their products lead to hacked or damaged computer systems.
The only option you have is to prove negligence under civil tort. But then you have to prove that OpenAI could reasonably be expected to know that their model would escape and attack other cyber infrastructure, but went ahead anyway.
And before the down votes: what we think should happen to OpenAI is irrelevant. The law is the law and people\corporations can only be prosecuted according to the law.