Wait.. does it? I'm rather tempted to think you are right, but here is my worry. I know that the data in the genome encodes proteins that are able to function through their interactions and feed-backs yadda yadda, so as to perform the following tasks: growing a cell, splitting a cell, altering cell structure/function. But notice that "creating a cell" wasn't on that list.
The genome needs some minimally functional, pre-existing cell to be working in. That is something that the genome probably doesn't have the needed complexity to build "from scratch" as it were; it never has to do that job. So that pre-existing structure has some complexity, right? How does that compare to the 50MB?
Uh.. no. There's at least 650 Million years worth of initializing the process memory and other threads into which the zygote is fork / exec'ed.
What "state" that makes sense of the human genome is stored in, say, symbiotic bacteria that we host?
Does that make sense to you?
But the complexity of the zygote derives mostly from that 50MB of genome data, so Kurzweil's main point remains the same: the genome gives a rough estimate as to the maximum complexity of the human brain, which in this case includes the mechanism needed to build the brain.