If you can sell your knowledge to an existing audience and then add a special category with a higher price for companies training LLMs why would you take the financial hit of selling to a single customer where they can now make demands of you as your only source of revenue?
I don't get your reasoning. First not all knowledge is the source of revenue. Many products and services are supported by know how to implement, use and maintain. This kind of knowledge can benefit from protection.
And if selling knowledge is the main revenue, why would transferring it to an LLM mean losing the opportunity to sell it multiple times? Au contraire.
For any category I assume the owner of the knowledge keeps in control and my case is that a LLM can be beneficial for them.