I've attended somewhere around 25 academic conferences over the past ten years and this is not my experience at all. I can honestly say that I have absolutely no idea where the overwhelming majority of historians, which I've become acquainted with over the years, stand on the bread and butter political and social issues of our time. In addition, I can't tell you where they stand in terms of religious affiliation. And to tell you the truth, I don't care where they stand on any of these issues.
In all of the sessions that I've taken part in, either as a presenter or as a member of the audience, I can't think of a single moment where a discussion of modern politics ensued or the conversation degenerated into a religious-cultural-social bashing free-for-all. What I do remember are countless discussions that broadened or deepened my understanding of a subject. In the cases where I presented a paper I almost always left with a clearer sense of my research's strengths and weaknesses. No one ever accused me of belonging to the wrong religion or political party, and I can't remember the last time someone asked for my stand on abortion. My guess is that the overwhelming majority of participants attend these conferences to discuss and learn about history.
My experience as an undergraduate and graduate student in history are also reflective of these observations. I attended classes in history at William Paterson College (now university), the University of Maryland at College Park, and the University of Richmond. All of my professors were professional and not once can I remember them engaging in the kind of behavior described in the media and blogosphere. I even worked as a teaching assistant for Jacques Pluss at WPC and never had any inkling that he was a member of a neo-Nazi organization.
I would love to ask the authors of these claims the following: (1) When was the last time they attended a college-level history course? (2) Have they ever attended an academic conference or took part in a workshop with academic historians? (3) Have they ever submitted an essay to a professional journal which would provide insight into how the vetting process works? (4) Have they ever witnessed the kinds of behavior that they describe? If so, did it occur enough times to warrant such generalizations?
There is nothing wrong with employing generalizations in an argument. However, all of us are able to detect a poorly-constructed generalization, and the difference usually boils down to whether a sufficient number of particulars have been properly employed. The problem in this case is that the authors of these claims have, for the most part, soaked up this critique from the mainstream media and passed it off as if they understand what it means, as if they themselves have experienced the behavior. In the end, these accusations are nothing more than a product of a defensive posture that views intellectual activity as a threat. Just below the surface you find ignorance and a whole lot of fear.