It's against the terms of service to do the generation, but the generated text is not copyrighted. Those are different things.
If I found an open port on a government computer it is still illegal for me to access that isn't it? Is the difference that this is port 80/443 and happens to serve HTTP requests something that has been described in law or court?
FYI: here are the relevant parts from the TOS:
(iii) use output from the Services to develop models that compete with OpenAI; (iv) except as permitted through the API
sounds like you are allowed to as long as it's from the api, as this "imaginary" restriction isn't in https://openai.com/policies/api-data-usage-policies, or https://openai.com/policies/usage-policies.