"I hypothesize the performance problem is in X. I predict if I add instrumentation Y and Z, it will show X is wasting several milliseconds per frame. My testing..."
"I hypothesize a blue background will be liked more by our users. I predict using a blue background will increase our retention rate. My testing..."
"I hypothesize the following invariants will hold about the code I've just written. I predict if I write these unit tests..."
"I hypothesize game mechanic X will be lots of fun. I predict if we build this prototype, ..."
For being "pure math", we're sure using the scientific method a lot. And measuring the real world. And decision-making based on empirical evidence. If your argument is there isn't enough science in computer science education, I might agree.
But then there are questions like "what's the impact on static vs dynamic typing on bug rates and productivity?" - in our current state, this is not computer math. It's not even on the mathy side of computer science right now - it is closer to being computer philosophy. We lack the experiments (can't control the other variables for A/B testing programming languages without perhaps actually writing bespoke programming languages for that very purpose!), and we've had a relatively short time to build our models of the computing universe... we're perhaps still building out the math necessary to create all those models...