Excellent point.

For me, the problem was one level before yours: I had very bad priors. This is embarrassing for me because (a) I frequently play chess at a USCF affiliated club and have read more than a handful of books specifically on the King's Gambit; and (b) I am a computational science grad student and have studied complexity theory in great detail, even specifically discussing implications of chess on the development of A.I. and complexity theory as a whole.

In retrospect, as @gjm pointed out, there are enough markers in the article (especially the "Turing machine program" reference, which should have been an absolute dead giveaway for me) to see easily that it must be a hoax. But in the larger sense, the article sounded extremely plausible to me. My prior belief was that the number of continuations larger than 15 moves long that truly need to be deeply explored is very small and that it shouldn't require too much computation to get to Rybka's standard of +/- 5.12. In reality, the number of continuations that would need to be examined is far larger than I thought, and chasing them all down to +/- 5.12 would probably require more computational resources than we have on the planet if you wanted to solve it in 4 months of actual time. It didn't occur to me to question this at all. I just thought "humans are smart at knowing what needs to be explored" and "Rybka is really good at knowing if a line loses given its positional score", both of which are gross oversimplifications that matter greatly if the claim is to have "solved" the opening.

I was also partially primed to wish that the result was true because of the mention of Bobby Fischer's hubris, something that I kind of want to see vindicated in a "there's-just-something-special-about-human-geniuses" kind of way, when really I should drastically discount a human's ability to completely refute an entire opening.

I am interested in whether there is a more general principle that emerges here. Because I am both a chess fan and a computer fan, I was more willing to overlook tiny discrepancies that should have been glaring. Almost like a version of halo effect but applied to my favorite hobbies. "Of course an awesome result in my nerd interest areas is likely to be true..." If the article had been about some new breakthrough in computer vision machine learning (something I'm much more internally skeptical about, though similarly knowledgeable compared to my knowledge of chess and complexity theory), I think I would have been much more interested in disputing the article instead of celebrating it.

Now the question is with respect to what other interests/hobbies of mine am I exhibiting this same error? As a person becomes more knowledgeable about topic X, we know that can lead to confirmation and sophistication bias, but can it also lead to something like celebration bias?