I don't buy it, but it still satisfies the particulars. And I am quite bitter that GWB has put us in this position. Enough time without a better explanation, and I'll probably start to buy into it.
For now, I prefer my "noblesse oblige" theory, wherein the Bush dynasty fancies themselves some sort of Messianics to the Mexicans, due to their energetic use of them as house servants. Think that's too weird? You ought to know a few Southwestern aristos (McCain, also) and how oddly attached they get to their house help. Servant guilt.