Yes at the end its just some data representing user's trained model. Is there a contractual agreement with users that apple will never ever transfer a single byte of those, otherwise huge penalties will happen? If not, its pinky PR promise that sounds nice.
But what does that have to do with the price of milk in Turkmenistan.
Because Boeing's issues have nothing to do with privacy or security and since they are not consumer facing have no relevance to what we are talking about.