One of Kurzweil's arguments in his response is "...the design of the brain (like the rest of the body) is contained in the genome. And while the translation of the genome into a brain is not straightforward, the brain cannot have more design information than the genome"

However the brain's design information is the genome, the laws of physics and a universe.

You only have to look at protein folding, and the complexity of the resulting molecule and how that interacts with the rest of the world, so see how much complexity is there outside of the genome - and it's that complex end result that you have to simulate or replicate.

He goes onto say that "..the amount of design information in the genome is about 50 million bytes, roughly half of which pertains to the brain. That’s not simple, but it is a level of complexity we can deal with and represents less complexity than many software systems in the modern world."

As above, this is greatly simplifying the end result that you're trying to replicate - the genome is just the software that's running on the OS/hardware of the universe. To replicate that virtually we'd also need a virtual universe.