Despite the test itself being flawed (as most tests are), a 10 point gap seems pretty significant, even if centered at about 100. Probably like 40th percentile vs. 60th percentile... but I'd need to look at their research further.
I think that, in all of society's major institutions there is a process that is described more or less by the Noam Chomsky article at this link.
Liberal domination of major institutions isn't a function of intelligence, but a function of cultural gatekeeping. Same goes for conservative domination of big businesses.
There's also the general theory that people in power tend to have higher IQ anyways, regardless of political persuation. The defendants at the Nuremberg trials were administered IQ tests by the U.S. Army. Long story short, the average score was 128 - with Hjalmar Schacht's 143 as highest and Julius Streicher's 107 as lowest.
As soon as I saw this thread, I knew someone would make some comment about "common sense".
"We grow up thinking that beliefs are something to be proud of, but they're really nothing but opinions one refuses to reconsider. Beliefs are easy. The stronger your beliefs are, the less open you are to growth and wisdom, because "strength of belief" is only the intensity with which you resist questioning yourself. As soon as you are proud of a belief, as soon as you think it adds something to who you are, then you've made it a part of your ego."