You misunderstand stand completely. The context was a person providing an answer to a question that was, for him and by his own admission, completely unknowable. This is the distinction. You do not postulate answers for the unknowable, only for the unknown. This is in stark contrast to a scientist giving up at his trade.Seriously? How would civilization have evolved if we all stopped at "I don't know."?
You either stop at "I don't know" or you move the science forward. You do NOT say "so someone had to kick it off" or otherwise throw your hands in the air or guess. Not productive or informative. Guessing does not move civilization forward. Reasoned thought does. If you do not know the square root of 2, you do not postulate that the answer must be "green." You either start multiplying numbers together until you get there, or you say "I do not know."
I most certainly am NOT one that stops looking. My career has been one continuous science project, and that is still how I make a living; testing, evaluating, and looking deeper. But I don't just guess. I either find the answer or say "I don't know" until I collect enough information to form a meaningful and defensible hypothisis.