The sentence before says: "I think I know too much" and that bogs down his creativity and energy. I'm calling bullshit. Who knows too much? How can you know too much? Does gaining knowledge really prevent one from being creative or energetic?
I think he comes closer to a point when he says: "it’s my attention to that knowledge which is destroying my inspiration." But I think its not the attention to the knowledge that is "destroying" his inspiration, but the way in which he uses that knowledge.
Why not give attention to the vast amount of knowledge gained writing web apps since IE4, and then use that knowledge to create novel ideas or better ways of doing things? Why not use the knowledge to create something better than JavaScript instead of complaining about it?
I think the point to take from this, at least for me, is to keep an open mind. He sort of said things contrary to that multiple times, but I want to believe thats what he was getting at.