They cannot actually do this as long as they keep Claude code open source. It is always going to be trivial to replicate how it sends requests in a third party tool.
Have you seen the "you wouldn't steal a car" ads? Or this video? https://youtu.be/IeTybKL1pM4?si=utZ5KjmK-C2-fFdP
The hard part is that they have an Anthropic-compatible API that’s different than completion/responses.