What does ‘valid’ mean. Notice that Mung’s post started with “what’s wrong” with but then just appealed to people making arguments.
If ‘valid’ is often used in context of logical deductions, where Mr Google says:
But that does not seem to apply here since there is no deductive argument stated.
Maybe ‘valid’ is meant to refer to a scientific argument? Science is about Inference to the Best Explanation and in the case of the eye evolution is a much, much, much better argument than instantaneous appearance. And in general, justification/best explanation by intuition is not science (although informed intuition is part of scientific process – Feynman is said to have claimed he started by guessing new equations).
Or perhaps you meant, would the person with good intuition have known the fact that made the argument correct. If knowledge is justified true belief, then Mr Gettier would say no, lucky guesses are not knowledge (justification is lacking).