No, I wouldn't say the group is representative, although on the other hand, it's certainly not just a small fringe group either.

However, I don't have in mind just people who actively contribute to such nonsense. Another problem is that similar intellectual failures about other topics would be (for the most part) correctly identified and criticized without causing bitter controversy and discourse breakdown, and a mass of other readers would also express correct judgment at least with upvotes and downvotes. So even the general passive approval is, in my opinion, indicative of bias, since such passive approval would certainly not be given to various other things that are not significantly worse by any reasonable standards.

Another bias that's clearly visible is that when someone displays intellectual failures of similar magnitude in various other areas, this would be taken on LW as indicative of an irrational person who is altogether below the universal standards of rational thinking practiced here -- whereas nothing similar occurs when it comes to these topics. Of course, I don't think people should be written off as general intellectual failures just because they demonstrated irrationality about these topics, but it definitely should serve as a warning for those who sometimes do apply such standards in other situations.