By dumb I mean unintelligent/stupid. I agree with your point, and do not think people dumb who have informed themselves through research and used reason to come to their conclusion, whatever that conclusion may be. The problem, at least according to the summary's quote from TFA, is that those surveyed who didn't believe in the theory of evolution agreed that, "humans and other living things have existed in their present form since the beginning of time". Someone coming from that position has a lot of explaining to do to get off my "you're an idiot" list.
The second problem, and I'm only assuming this is the case, is that the majority of anti-evolution proponents surveyed probably feel that way due to religious conviction/dogma/doctrine rather than rational thought and scientific inquiry. That will also get you on the idiot list. I know plenty of insanely religious people that are highly intelligent, rational people. Most of them also see no conflict between religion and science, except through the lens of the ignorant and/or stupid. There are plenty of scientists, many well-known, who are also religious. If they were to reject the theory of evolution it would probably be for a scientific reason rather than religious conviction. I have no problem with that.