It shows Republicans as smarter than Democrats

Kind of; the great thing about those distributions is that you can talk about more of the distribution than one summary statistic. There's a clump of high IQ democrats, a clump of low IQ democrats, and then a clump of medium IQ democrats, whereas the Republicans look like one clump of medium IQ republicans. There are more Democrats from 0 to 5, more Republicans from about 6 to 8, and a tiny few more Democrats from 9 to 10.

This matches with the prediction that there is a significant group of low-vocabulary people who vote predominantly Democratic, the middles voting somewhat more Republican, and the highs about evenly split.