Nice to see you've read that article with such a high degree of comprehension. But apparently missed the significance of one of the key phrases
"So then, the question is, why do people deny this? ... if your answer to that question is, "oh, because they're stupid" -- well, you're wrong."
The point of the article is that motivated reasoning is the cause of a lot of the mismatch between what certain people say - and that it certainly occurs in all areas and that no-one is immune. But science is itself an attempt to get over that hurdle by measuring against reality and having an open debate over the actual data.
The reason I linked Chris Mooney is that Lewis' article attempted to counter "The Arctic is melting" message with a "The Antarctic is growing" message, even though that message is partial and inappropriate in this context, and I believe anyone who actually looks at the data and pulls this argument out of it is deliberately blinding themselves. Hence, reliance on it appears to come from motivated reasoning.
Of course, the chances are that Lewis' did not look at the data, but simply repeated what he's heard from other sources that he liked the sound of. This is what most of us do, certainly it's what I do, as I don't have the time or inclination to actually look at the data myself and try to parse it.
If climate science really is such a mess, you should be able to pick up a bounty here by showing it: