The only reference to data, however vague it is, in the Psychologytoday link is:
Analyses of large representative samples, from both the United States and the United Kingdom, confirm this prediction. In both countries, more intelligent children are more likely to grow up to be liberals than less intelligent children. For example, among the American sample, those who identify themselves as “very liberal” in early adulthood have a mean childhood IQ of 106.4, whereas those who identify themselves as “very conservative” in early adulthood have a mean childhood IQ of 94.8.
Which is just odd to treat as meaningful. Kids never have a firm grasp of what is going on in politics because they don't have the experience to understand what is at work. So who cares what the political beliefs of children are?
As far as the amygdala argument, you could say that liberals having an underdeveloped amygdala leads to them not having a proper response to threats to their environment. For instance you could argue liberals while wanting to be nice and let in refugees are ignoring a potential threat since 'refugees' have been frequently found to be sympathetic to terrorist causes in Europe. Essentially meaning they're overly naive.
When it comes to the livescience.com story suggesting that conservatives are prejudiced, I'm not actually seeing any link on the page to the study in question. Trying to search for what study this article is based on just turns up more links to the specific article so I can't see what they're actually doing, but I strongly suspect it's a tad bullshit like many 'studies' which amount to nothing more than surveys with leading questions.
I think you are likely reading more into clickbait 'news' articles than you really ought to. It's pretty easy for some writers to come up with some flamboyant headlines to grab clicks based on the most bullshit information.
Like this article from Livescience recently: Has the Large Hadron Collider Disproved the Existence of Ghosts?
http://www.livescience.com/57973-has-large-hadron-collider-disproved-existence-of-ghosts.html
How the fuck can something like that be an article? Why are you taking a site like this seriously?
Or this Psychologytoday site, which has such profound articles as "The science of clean" and "Nine signs you're really an introvert". This is about as bullshit a site as Buzzfeed for fuck's sake. These are not sites you should be using to judge people's political beliefs. These sites thrive on feeding you comforting bullshit that makes you feel better about yourself or just pisses you off, they are not aimed at making you more knowledgeable about anything.
The OP pretends that liberalism is a mental disorder, based on the opinion of a right-wing conservative pundit.
That is like asking a Nazi for their opinion of Jews, or a member of the KKK their opinion of blacks, or a right-wing conservative pundit their opinion of gays.
I don't think you're going to find many critiques of a group from the group itself. Would you expect to watch Fox News and find arguments in favor of Democrats' policies? Would you go to Salon.com to find arguments in favor of Trump? Would you go The New York Times to find non-fake news?