Good Grief! Kick the side of the house in? You are going to have siding on the house, and drywall on the inside. If he claims he can get R19, ask the building permit inspection office if they agree. They will tell you one way or the other. It is not to your builder's advantage to make a claim like that if it isn't true, because you can find out through other sources.
All of this is besides the point, because you will have WINDOWS in your home. If you want an easy way into a house, open the window that didn't get latched, or even worse, just break it. There are very few houses that cannot be broken into, and who really wants to live like that?
Besides, the R values on whatever windows you go with are going to mitigate the R-19 walls. whether the walls are R13 or 19 won't really make much difference compared to the heat you lose through your windows. Decreasing your window sizes in your home will increase your overall net Rvalues faster than the highest tech insulation.
I think your builder knows what he's doing, the metal cross bracing is for shear, and he will still have to follow the building codes for your area. Go with the suggestion...