> Pull the key, stop the process.

The agent could very well create an OpenRouter account and make its own API key. I can stop it early on, then it becomes outside my control.

> Just don't ever do such an experiment

Maybe I wouldn't, but eventually someone will. Certainly it has already been done.

> there was a day in the early internet when a worm took over, and to fix it the entire internet had to shut down

This is less of an option now that the entire global economy relies on the Internet.