A couple of points I'll throw out:

1. SF forces are great for developing the capablities of an indigenous military force, and that comes at the point of picking sides. What sides would have been chosed had internecine fighting broken out immediately between the Shi'a, Sunnah, and Kurds. Three brigades would have been hard pressed, and it takes like a division (-) to manage Baghdad alone right now?

2. Could we have sustained the employment of SF forces for the almost three years we have been in Iraq, taking into consideration the demands in Afghanistan? It's a simple matter of looking at troops to task. I don't know the composition of 5th Group, but we are not talking about an inexhaustible supply of teams to continue engagement with the populace for an indefinite period of time. At some point the big green machine, as cumbersome as it may be, has to assume some of the responsibilities inherent in re-building a country. SF simply can not do it alone, in my opinion.

3. An SF element went into the town of Ar-Rutbah near the Syrian/Jordan border and executed probably a classic mission to make contacts, organize local governance and basic services, but it was before the insurgency built up its steam. By the time my unit arrived (two rotations after the 82nd Airborne) the town had slid into a nest of low-level insurgents who would kill the mayor just as easily as they would have killed a Marine. Without a sustainable Iraqi Security Force structure (which by the way DID GO AWAY once Saddam fled), I think it's highly improbable that any number of SF personnel could have maintained security for long. If your discussion partner had his way, the result may have been a hodgepodge of reaction forces tied down everywhere, and getting absolutely nothing accomplished.