I was merely commenting that he didn't try to make his opinions sound like science. I usually see this from the left - such as the studies showing Republicans are more "authoritarian", etc.
I don't know, it sounds to me like that's just what he's trying to do, starting with the title -- "The Liberal Mind: The psychological causes of political madness" and moving on to this: "As is the case in all personality disturbance, defects of this type represent serious failures in development processes."
The thing about such off-the-cuff analyses of large groups is that they're always true about somebody. But the kinds of analyses constructed by the other side are also always true of someone as well. So abstract attacks from one side and the other balance out.
On a specific question, someone's political opinions may very well amount to madness, but it's a lot harder to say that about an abstract political tendency, unless you want to turn it into a cliche, which he does. In some situations ways of thinking that could be categorized as liberal are appropriate, in others they aren't. It doesn't look
There's nothing wrong with the conflict of political opinions, but dressing opposing views up as pathologies is a mistake, whoever does it, if only because it replaces arguments with dismissive labels. Even if one is right, eventually the arguments fall away and all one has are the labels.