Computer science largely deals with algorithmic space and time complexity. Look up the Wikipedia page on logistic regression and tell me if you see computer science there.
It is true that software giants are using and making huge breakthroughs in ML, specifically deep learning. That's largely because these companies invest heavily in bringing in the top ML researchers to their teams. Do you know the cost of deep mind? Individual engineers on the team have had multimillion dollar golden handcuff contracts from what I heard.
Yes, software engineers can utilize the developed theory of ML and apply it to applications. For example, look at the new Google image search. You have a lot of interesting filter options now that require machine learning. Google speech recognition for instance has gotten so much better because Google moved off GMM's to dnn for the decoding.
So just because Google and FB have interests in ML, doesn't mean that ML is a CS discipline. That's such faulty logic.