For an AI system to be “completely safe”, like a self-driving car, it must map the full environment it operates in and be taught the “right way” to handle every conceivable scenario.

So when you present it with novel data or a situation, that constitutes an “AI safety event”, which per their ToS is a carve out for training on your session.

Further, go read the ToS carefully about what you opt out of. You’ll note there’s nary a mention of tool calls. You’re only opting out inputs (what you type) and outputs from the model from being trained on. All the content of the tool calls made while running on your system are fair game for training.