I can't agree with that conclusion. There are plenty of brilliant idiots and idiotic geniuses in the world and it can often be more difficult to change the mind of a "smart" person who has drawn the wrong conclusions than a simple person who has done the same. Individuals who draw their sense of self-worth from their perceived intelligence a more likely to stand their ground, argue semantics, and log every cheap rhetorical grenade they can until they are blue in the face.
For evidence of the irrationality of intelligent people, I proffer the example of every pointless university faculty departmental meeting, ever.