Yes, that is quite pedantic. It is clear from the article that Betteridge meant headlines that could be phrased assertively but are not (i.e. yes-or-no questions).
And the word "universal" is generally scoped to some domain — if we say "living human brings universally have some cardiac organ, whether natural or man-made", that does not extend to dead human beings or to rocks. In this case, the domain is, as noted above, newspaper newspaper headlines that question an assertion.
Your domain was scoped by the "living human brings(sic)," that is why it is clear that dead people or rocks where irrelevant. I have always taken universally to mean as wide of a scope as possible.
I was not sure where you where referring to when you said "as noted above?"
The two pg essays I linked to could have been an assertion but the answer did not seem to be no, but I could be wrong. From the quick essays of pg's that I read he seemed to use the question mark for pieces that required a much more nuanced answer than yes or no.
And the word "universal" is generally scoped to some domain — if we say "living human brings universally have some cardiac organ, whether natural or man-made", that does not extend to dead human beings or to rocks. In this case, the domain is, as noted above, newspaper newspaper headlines that question an assertion.