He has a point in general that the US would probably be more reluctant to fight wars if the average person had to actually fight them.
AGAIN, the military IS a near perfect cross section of the US at large. It's full of "average" people.
I would love to see some data on this reflecting parental household income and educational attainment, and compare it with either party's caucus in Congress. Not many children of congressmen or their donors are enrolling because they need tuition money for college after their service, are they?
How many members of the Romney family go into the service as opposed to a family in, say, rural West Virginia or Pennsylvania?