It is to some extent if we have a constant time example in real life. If the AI can't solve protein folding fast enough it can just design absurdly fast protein sequencers and really good microscopes and get proteins to fold themselves in real life and use the results in the rest of the computation.
I agree. I wasn't thinking about finding a constant time algorithm, though - more of finding an analog circuit that would mimic the behavior. After all, proteins don't actually fold by following an algorithm; they fold by responding to physical forces.