Myers is attacking Kurzweil on the assumption that Kurzweil is actually proposing that the brain's structure should be reverse-engineesed from DNA, which would be intractably hard. Only Kurzweil isn't saying this anywhere. Instead, he seems to be using DNA as a measure for the amount of irreducible complexity that needs to go into a system that will end up with the complexity of a human brain.
This is like saying that the underlying complexity of the Mandelbrot is the set of pairs of real numbers.
Since, going by your analogy, we're talking about how hard it is to build a machine that will draw us the Mandelbrot set, isn't that exactly the point?
This is like saying that the underlying complexity of the Mandelbrot is the set of pairs of real numbers.