It's a simplification, like any analogy. It's also a version of Brooks' Law[1], in case that wasn't apparent to all.
Businesses can certainly scale with more people. But this isn't a business, and to loosely paraphrase Andy Bechtolsheim at startup school this year, throwing money at problems is lazy, you should be throwing minds at problems. $41M in the bank will almost certainly be harmful at this stage of Color's development.
Also, even $41M is not going to (noticeably) speed up the surrounding ecosystem.
Because, like pregnancy, businesses can't scale with more people?
It is well established that certain work scales almost linearly with more people. But it is also well known that a lot of other types of work do not at all scale when you throw more people in. Usually it is intellectual tasks, like programming or turning a startup into a profitable business, that don't scale well.
It's a classic b-school aphorism. He's not really trying to defend an analogy. He's saying, "it is not necessarily true that more money will scale this faster; there are probably other limiting factors". Don't be so quick to jump on him.
I think the aspects of a business that don't scale are how user behavior evolves over time. It takes awhile for groups of people to try new things and figure out all the different/awesome ways to use something (Twitter and @replies, RTs, etc are one clear example).
Can 9 women produce a baby in one month?