It has been proven that a Turning Machine and Lambda Calculus have the exact same equivalent expressiveness, that encompasses the _entire set_ of computable functions. Why are you so sure that "text prediction" is not equally expressive?
Was Hellen Keller not intelligent because she lacked the ability to see or hear? Is intelligence defined by a particular set of sense organs? A particular way of interacting with the environment? What about paraplegics, are they disqualified from being considered intelligent because they lack the same embodied experience as others?
Whenever you give someone kudos for being brilliant, it is always for their ability to successfully compute something. If that isn't what we're discussing when we're talking about intelligence, then what are we discussing?
On the other hand, you are clearly stating that intelligence is computation. But you're right, it would be too easy to ask you to define what any of those words mean AND to back that claim.