I would think it is more 'did not feel fitting for this story' than 'missed'. He isn't mentioning any other parts they built on either (Cocoa, the Mac OS Unix-based networking code, the font designers for Mac OS system fonts, the GNU project for gcc, K&R's progamming language design, etc)
Shipping a browser in a year, starting with a browser, is less impressive than shipping a browser in a year starting from a GUI toolkit.
(To be fair, Mozilla shipped a browser in a few months after founding, and Konqueror didn't work well enough for me to use it as my primary browser at the time that the Safari guys took it. And, as the other comment pointed out, it actually took the Safari guys a couple of years.)
In the context of the story that is irrelevant, and it is actually not correct. Don Melton started at Apple in the summer of 2001 (the same day I did). At the time of this story they had already been working on Safari for over a year, the point was that in that meeting they realized that Alexander was less than an additional 6 months away from shipping.
Not to discount the work of the kHTML guys, but it was more than a year of work to get from kHTML to Webkit.