I do think that distilling a model from another is much less impressive than distilling one from raw text. However, it is hard to say if it is really illegal or even immoral, perhaps just one step further in the evolution of the space.
It's about as illegal as the billions, if not trillions of IPs that ClosedAI infringed to train their own data without consent. Not that they're alone, and I personally don't mind that AI companies do it, but it's still amusing when they get this annoyed at others doing the same thing to them.