The title is a pun actually, as the E8 group is technically both "exceptional" and "simple", in the mathematical sense of those terms, if i recall correctly.

so the title is a joke of sorts.

I didn't bookmark it and can't immediately find it, but I saw him say that he would be very surprised if his theory was universal truth and that the probability of him being correct was low -- but he thought he had a better shot at it than string theory.