I agree, both regarding timescale, and regarding reason for timescale difficulties.

As I understand Kurzweil, he is saying that we will build the AI, not by finding the program for development and simulating it, but rather by scanning the result of the development and duplicating it in a different medium. The only relevance of that hypothetical million-line program is that it effectively puts a bound on the scanning and manufacturing tolerances that we need to achieve. Well, while it is probably true in general that we don't need to get the wiring exactly right on all of the trillions of neurons, there may well be some where the exact right embryonic wiring is crucial to success. And, since we don't yet have or understand that million-line program that somehow gets the wiring right reliably, we probably won't get them right ourselves. At least not at first.

It feels a little funny to find myself making here an argument right out of Bill Dembski's playbook. No free lunch! Needle in a haystack. Only way to search that space is by exhaustion. Well, we shall see what we shall see.