I don't doubt the validity of Dwork's work. I think we're talking past each other.

What I'm saying is that if Apple keeps data on its servers that is sufficient to predict some of my actions or likes with any accuracy greater than 50%, then that is a privacy concern.

But if you're saying that the data in Apple's database does not have any predictive power on its own, then I agree that it is not a privacy concern.

In that case, my device would have to download some of Apple's data and combine it with data that resides only on my device in order to make a prediction locally on my device.

If that's how it works then I have no concerns.