Rather than quibble with this erudite Offering, I will only point out that since the tetragrammaton of infamy is descended, rather directly, from an Indo-European root meaning 'to pierce with a spear', the primary overtone of the word has always been antagonistic. Hence, it's close linguistic cousins are 'feud, fight, foe, and frigate (the warship variety)'. Robert Graves, in his section on the Dactyls, in The White Goddess refers to it as 'the fool's finger', "because there are more fools than anything else". Graves associates the thumb with the phallus.

About.com may have confused 'the finger' with 'the fig', a similar gesture still used in some Mediterrnean countries. 'The fig' is made by extending the tip of the thumb between the first and second fingers. (Information from my annotated copy of The Divine Comedy by Dante, in which a demon uses the gesture.)