Actually, I thought yours was a pretty fair one too. But not necessarily just because the guy didn't know those things. Yeah, for someone in the U.S. his age to not know those things is pretty surprising. But a lot of people don't know a lot of things that you would thing would be "common knowledge." But what is astounding and makes the guy look dumb, IMO, isn't the fact that he didn't know. It's the fact that he was adamant that he was right. There's always something we are ignorant about. Ignorance doesn't necessarily make someone look foolish. It's when one insists that their view is correct when it clearly isn't that their ignorance becomes willful instead of accidental, and they end up looking like a fool.
Yeah. There's nothing really wrong with not knowing something, but you'll never actually learn and correct that lack of knowledge if you choose to remain ignorant. This guy wasn't looking to learn, he was only looking to be right, so as you said, it just becomes willful ignorance at that point when he refused to accept truth.
I suck at geography, and I know it, so if someone corrected me on a point of geography, I'd take their word for it over my own (well, unless you told me something really silly, like Australia being part of the world).