If you can prove that your LLM did not learn from the patent (eg cut-off for learning was before), then the LLM outputting the algorithm (or product etc) would

If you can prove that your LLM did not learn from the patent (eg cut-off for learning was before), then the LLM outputting the algorithm (or product etc) would be pretty good evidence that a practitioner of ordinary competence in the field, or whatever the exact legal wording is, found the whole invention to be trivial.