No he isn't. He's talking nonsense to peddle a pedantic point of view.
So lets add ad populum to the list of fallacies that are raining down on this thread.
It's nothing to do with pedantry. He remains correct. Sometimes it's good to go back to basics to remind ourselves of certain matters. In this case, Thomas Henry Huxley's classic and indeed original words about
Agnosticism: "Humankind can have
no knowledge, except of phenomena". The phenomenal world is all that we can
know. There are various claims made about the supernatural world, but we can
never know that they are true. Most persistent religious beliefs arise because of certain observations about the natural world. NS's suggestion that the world
could have been made by a psychopathic nutjob has formed the basis of certain religions and arises from the very obvious fact that the world is replete with undeserved suffering, (and the God of some of the OT is depicted as behaving as if he were the said deranged sadistic monster - and so does some of the NT). The basis of Gnosticism depends on such perceptions. Christianity's response to the world's suffering is that we're being tested here, and that those who "play by the rules of the game" will have everything made good for them. None of these beliefs can ever be
proved . They are supernatural claims, and are on a completely separate level from those made about the phenomenal world. As such, your conflating NS's hypothetical suggestion (in which he does not believe) with the idea of that the earth is flat is demonstrably in error. We can
prove the world is not flat; we can
prove that the moon is not made of green cheese, and we can
prove that little boys are not made of slugs and snails and puppy dogs' tails.
As for your comments about the
ad populum fallacy: I had suspected as I was typing my post that some inattentive reader might accuse me of falling into that. I did not suspect that the said inattentive reader would be you.
