This kind of thinking is by no means unique to the contemporary right. But it is ubiquitous, and the staying power of the Oregon petition indicates way. Even the silliest claim, once made part of the canon must be defended to the last. In extreme cases, there is the option of dropping an utterly discredited talking point and then saying “we never said that”. This is one thing the Internet has made much harder, with the perverse result that obstinacy in error has become more entrenched.
In a follow-up post he looks at whether it is possible to find a similar example on the left.
Update: Here is a picture of the Oregon Institute of Science and Medicine and its staff: