Microblog Memes

He's best known for a blog on rationality called LessWrong, Harry Potter fan-fiction written as a vehicle for his notions on rationality called Harry Potter and the Methods of Rationality and being more than a little obsessed with AI risk and being behind the Machine Intelligence Research Institute. He's also written some other fiction that's broadly not bad, including a piece about first contact called Three Worlds Collide and an isekai Japanese-style light novel called A Girl Corrupted By the Internet Is the Summoned Hero?!. He once wrote an April fools post where he claimed to be from an alternate universe and for a one off April fools bit contained a surprising amount of world building.

None of the above implies he is actually human, let alone is familiar with where common human foods grow from. I could totally see him being exactly clueless enough to assume that since holy fuck are a lot of foods technically cultivars of wild mustard, that potatoes and apples are similarly related.

Not a physicist. I suppose you could call Yudkowsky an anti-AI activist. And/or world-famous fan-fiction author. These would be strange but technically accurate ways to describe him.