I would like to see some evidence that this is the case. As for the link above I couldn’t get the PDF to come up. So, I’m left with posters opinion. Which, speaking of bias

I’ll take with a grain of salt.
People migrate to professions of their choosing. The brighter, and more educated have, I assume, the most choice.
My neighborhood is pretty much working class by the way. I know most conservatives think my neighbors are over represented by liberal thinking. They would be right. Until they start with the free stuff from the government rhetoric. My neighbors are not lazy, or on the dole. They work hard, and look after their families the best they can.
So, I don’t meet an awful lot of conservatives at home. But most I do meet are the TEA party/talk radio variety. Mostly they just regurgitate what someone else has told them. This is not critical thinking by the way. I really like it when they complain about how America has fallen, as they unload the things they just bought at Walmart. Again we see an absence of critical thought. (There have been a few studies conducted to try an discover what causes a person to act against their own welfare.) I think these people could have used a thought provoking teacher or two when they were coming up. The funny thing about this is that I meet some very successful businessmen who show the same lack of critical thinking. To me they come across as whiner’s, and spoiled children, who are preoccupied with grubbing for money. What person who is thinking critically, argues about something that has been a violation of the International Fire Code for two decades? Or demands a variance?
The question of impressionability in college aged students is an interesting one. We know not to assume that every youth is impressionable at all. At that age some think they already know everything anyway. But unless they are given the opportunity to hear a variety of views, and judge them on their merits. They will not have the tools to make rational choices.
ATB