This is as effective as saying "X is a branch of philosophy", where X is any discipline. It's probably true for every discipline, but what's the point?
Also every X is a branch of physics, because we live in a physical universe and everything is inside it (so even pure mathematics is a branch of physics).
And finally X is a branch of computer science because computation and information processing sometimes appears to be more fundamental than everything else. E.g., physics cannot answer the question, "are we living in a matrix-like simulation?" but if we really are, the whole physical universe is mere computation happening in some higher dimension.
I like to think of Mathematics, Computer science, Physics, and Philosophy to be deep and insightful realms of human thought, and they have many connections but also many unique attributes.