Note that he's saying that the red states gave more *as a proportion of income*, not more in absolute numbers. Of course, even the red states are almost half blue, and the blue states are almost half red, so I'm holding out for a better study. Not that it's not a good point. We've known for ages that the wealthy give smaller proportions of their incomes.
Even in terms of pure "Giving Rank", the highest blue state is #9.