You're right that it's not entirely novel, but it is useful, at least for Claude users: there's quite a bit of research showing that training models to self-censor makes them dumber, and so putting the censorship into a separate model (and allowing Claude to use its full intelligence for the "safe" queries) is a fairly useful change assuming it works well enough to prevent further lobotomization of the chat model.

(Of course, open-source models are even more useful...)