I have no problem admitting it was not the most polite response. Do you think HN would be corroded by people flooding HN with AskHNs anytime they are curious about something but can not be bothered to do the most cursory of searches on their own? I do.
I typed the AskHN title verbatim into google and was presented with a number of pages that explained the origin of the symbol.
No, I don't think it would be corroded that way. I (briefly) enjoyed answering his question. Whereas your response (briefly) made my blood pressure shoot up.
People frequently ask questions on HN that Google could "answer". When those questions spark interesting conversations, they get voted up. Otherwise, they fall off the front page.
A better thing to do than acknowledging that you were rude and then explaining why you decided to do that would simply be to apologize.
Please don't treat other people this way on HN. It's mean, and it corrodes the site for all of us.