What that sentence says is: Bell's theorem predicts the linear dependence of the correlations angles - or at least it's consistent with such a model. It's not a

What that sentence says is: Bell's theorem predicts the linear dependence of the correlations angles - or at least it's consistent with such a model. It's not an assumption of the theory. Also keep in mind we don't observe linear correlations - at least one of the assumptions of Bell's theorem must be wrong.