Thinking more about this, Jeff was saying "write for people":

When I write content, I do so in a way that comes natural. I don’t use certain words over others because they taste better to the spiders. I write as a human for other humans.

That's all. He wasn't saying SEO is crap. He was just saying "write naturally", that's all. Not sure how it got off onto a whole markup/theme/SEO topic. Write for people. That's it.