There is an interview where he explains what he likes about Emacs:

I have special Emacs modes to help me classify all the tens of thousands of papers and notes in my files, and special Emacs keyboard shortcuts that make bookwriting a little bit like playing an organ.

Probably one of the few rational vi/emacs arguments I've seen. And it also is a good reason why I like vi, given that I can barely hit two keys on a piano at the same time.

(Link to interview: http://www.informit.com/articles/article.aspx?p=1193856)