Would you trust a “physics scientist” who had no idea who Newton was?
In all fields there are people who have done great advances, their genius is such that it’s hard to learn about this things without knowing who they are.
I’d doubt that someone who had no idea who Alan Turing was (or at least that he was a person) has a deep understanding of Turing-Church machines or know about their implications.
Because it’s hard to learn about optimal algorithms (and proving such mathematically) without ever, ever hearing a reference to Knuth’s work has ever really learned a lot about efficiency, different techniques, and different algorithms. Moreover I’d doubt he’d know where to look for an optimal solution for a very strange problem (or realizing there is no such optimal solution).
I wouldn’t trust a “Linux Kernel Hacker” who doesn’t know who Linus is, or an open source “guru” that only returned a blank stare when he heard the name Stallman.
In every field there are great people, if you are into painting I’d expect you’d recognize a few know artists, Picasso, Magritte, Monet. If you were into music I’d expect that you know The Pixies, or maybe The Beatles, or maybe Mozart, or any combination, but I’d hope that you have heard other music and know it’s good.
Maybe we can’t recognize all the names, or all the things. But get a list of enough important people in a field, and you will find one that you not only heard of, but either admired, or detested, their actions and philosophy enough to remember them and recognize them.
Now it’s true, Atwood is stretching it a bit too far with such a limited list, maybe a better use of words, such as “I’d hope that any person who I’d hire would know at least one person in this list” but then again, is it surprising that he just went and said the first thing that came to his mind? Flame-wars are the publicity stunts of the 'net. So chillax people, if you don’t know people on the list, instead of arguing why you still should be a valid candidate for work, read about them, learn, become a valid candidate and then gain the pleasure of being the one who would return a rejection letter, in the end you can only become better programmers because of it.