ummm... I'm sorry if it's incompatible with your POV, but it's a fact. It's been true throughout history.
edit: Perhaps it would be more proper to say that intelligent people tend to be more liberal. Back to the causation vs. correlation argument.
Or, just a possibility, the study that found that to be true is flawed.
...more intelligent individuals are more likely to espouse the value of liberalism than less intelligent individuals, possibly because liberalism is evolutionarily novel and conservatism is evolutionarily familiar.
First, it fails to define liberalism v conservatism. Are they using the traditional definition of liberal, which is all about the individual over the sate, or do we use the modern definition, which is about the group over the individual?
Second, what is it that makes anyone think that liberalism is evolutionary novel? Evolution is about change, and the modern idea that conservatism opposes change sounds more evolutionary novel than liberalism to me.
Third, liberals seem to have a hard time dealing with the evolution of political power today. They are insisting that the old structures will work, and that the ultimate outcome of their policies is not leading to the problems it obviously is. Is it really intelligent to insist that conservatives are to blame for the problems that they had little to do with? Liberals have been in charge of the government, media, industry, and education for decades, yet things keep getting worse. Yet, somehow, conservatives are the less intelligent people because they refuse to acknowledge the inherent superiority of liberals.
There has been a debate for years about the validity of IQ tests. Perhaps the reason liberals generally score higher on IQ tests is that they are actually testing for liberal tendencies, and not actual intelligence.