Earlier quoted context omitted.
Why does an ML-expert need to know the halting problem? Considering that ML is really a CS-oriented form of statistics, why would you expect a statistician to know CS theory?
Thinking more, it's the misleading names ("machine learning", "AI") that rustle my jimmies so much. Sure, you don't need to know the halting problem to approximately solve MNIST by fitting a million-parameter curve to a dataset. But you're misleading people if you're claiming to have any kind of insight into how computers can be made intelligent, or how computers can "learn", when you don't even know the halting prob…
I'm working in the symbolic AI field, and sometimes use ML techniques. They are complementary. To me, ML is about induction, AI is abut deduction. They don't solve the same kinds of problems and they tend to work pretty well together.