I was confused by that too. I think I've figured it out.

They're saying that a public LLM won't know the email address of Jon Snow, but they still want to be able to answer questions about their private SaaS data which DOES know that.

Then they describe building a typical tool-based LLM system where the model can run searches against private data and round-trip the results through the model to generate chat responses.

They're relying on the AI labs to keep their promises about not training in data from paying API customers. I think that's a safe bet, personally.