Let's say that OpenAI used a shell company that hosts server where an agent spun up another agent on instructions from another agent which was corrupted by bit errors from the inference framework which caused some major hack to happen. Its impossible to investigate in the same way as physical issues. What if the model is open-source, who is responsible then? What if it's open source but another process altered the weights?
When you say infinite loops, you mean infinite indirection, but obviously no such thing exists, because computer systems, just like other physical things, exist in physical space, not on the astral plane.
Whoever had agency to start the domino effect carries the liability. Doesn’t matter if the model is open source or if you brewed it home. And if you weaponize OpenAI’s models through their servers, it would likely be shared liability. Yours would be malice, theirs would be negligence.
Which judge will go down the rabbit hole of figuring this out? How will they do it? Will they have people tracing logs over 5000$? And if they do get there, in your fictional world, at some point, after 1 year of investigations and back-and-forth, it's okay, the technology is beyond what it was before, it's not relevant anymore, new technologies and new methods.