Nomad is sl-o-o-o-w. That's basically why. It's like a 2-4 minute slower version of Default resources.
Furthermore, "place your TC defensively"????? That's beneath even you, Darth. You must ALWAYS place your TC next to wood and food, or you lose. You don't want to be even slower than normal for nomad.
One good thing on nomad, though - Roman is as fast as, if not faster than, Shang! You start with 200 wood and 200 Food. The Roman can use this to immediately build a house, whereas the Shang must gather 30 wood; in the meantime, the Roman will have gathered food, meaning he can catch up to the Shang. Well, at least almost.