Since EY claims to be doing math, he should be posting at least a couple of papers a year on arxiv.org...

Even Greg Egan managed to copublish papers on arxiv.org :-)

ETA

Here is what John Baez thinks about Greg Egan (science fiction author):

He's incredibly smart, and whenever I work with him I feel like I'm a slacker. We wrote a paper together on numerical simulations of quantum gravity along with my friend Dan Christensen, and not only did they do all the programming, Egan was the one who figured out a great approximation to a certain high-dimensional integral that was the key thing we were studying. He also more recently came up with some very nice observations on techniques for calculating square roots, in my post with Richard Elwes on a Babylonian approximation of sqrt(2). And so on!

That's actually what academics should be saying about Eliezer Yudkowsky if it is true. How does an SF author manage to get such a reputation instead?