First, the theory that your reference is totally wrong in that it has absolutely nothing to do with Panda. You, and the blogger that you referenced, are pointing out the well known duplicate content filter, it is not a penalty, there is no duplicate content penalty. The duplicate content filter has been in place for many years prior to the Panda update.
Some of the websites you cited as sites “that Google trusts… and knows that they will NEVER have duplicate content” are known to use massive amounts of syndicated (duplicate) content.
Finally, from the earliest days, Google has been very clear about what the Panda update was about. In case you missed it, here are some general as well as specific things that Panda targets: Official Google Webmaster Central Blog: More guidance on building high-quality sites
What I’m trying to say is that the author is conflating two unrelated things. Trust has been part of the algorithm for many years prior to Panda, the notion that a website is “Panda-Trusted” is the part that I see as rubbish. Not that there are not Trusted sites, just that it has nothing to do with Panda. When Panda hit it affected many “trusted” sites. Likewise, the Duplicate content filter pre-dates the Panda update by many years as well.
The author himself seems to confirm that his theory is completely invalid before he proceeds to explain in detail that invalidated theory:
|I deleted the entire folder after I determined that it was the only cause of the Panda penalty. … Nonetheless, more than 1 year later, I have not recovered.
This just leaves me scratching my head, wondering why I read the entire article since nothing was included that clarified why he clings to his obvious invalid theory. How can I get back the 7 minutes it took to read this rambling failure of logic?
The bottom line is that the Panda update had a wide-ranging effect on many websites, including websites that had no on-page content with Panda issues, but suffered due to relying on inbound Pagerank from other websites that were hit by Panda issues. Just because your own website may have no poor quality content, you can still be affected indirectly from backlinks that lost PR due to Panda. People seem to forget about that and come up with these baseless theories.