To get to the Beinecke's images of the d'Este from their site,
http://beinecke.library.yale.edu/dl_crosscollex/, search "d'este" and it's on p. 2. They have two images, one a low-res black and white. I would guess that this is not just a black and white image of the same card, but a different one, that had been printed but not yet colored. Trionfi.com mentions the d'Este card-printing machine somewhere. I doubt if it is a black and white illustration for an early printed book, because of the large amount of white in the image. (Compare it to Kaplan's reproductions of d'Allemagne's 1906 versions, Kaplan vol. 1 p. 118. For whatever reason, Kaplan does not have a d'Allemagne image of the d'Este Fool.) But I am no expert.
This image, interestingly, is something like a mirror image of the colored one.
The boy is definitely pulling down the loincloth, as might be permissible at Carnival, if the Fool acts unresponsive when the crowd says "Show us your c--k" (the wording used in New Orleans; I am not sure what the bounds of good taste are on this Forum, regarding words). But the boy also might be sneaking a touch, with one or more of his fingers.
For my analysis of the meaning of the gesture, I don't think it makes any difference whether he is touching or not. It is the outline of an artificial phallus under a cloth on the tray, as described by Clement of Alexandria and depicted on Roman sarocophagi, and perhaps the lifting of the cloth at some point, that matters. It is a sacred object and fertility charm, not to be defiled and especially not to be handled inappropriately, as the animal is attempting to do on the "Marseille" cards (most clearly in Noblet).
Daimonax makes a big thing of the touch, especially in the "Lover" card (where I don't see it implied at all, nor necessary for his point), in part based on its significance at Pompeii. For me, Pompeii is irrelevant, because it was excavated long after the cards were made; and even there, it is an artificial phallus that the girl touches--with her hand, over a cloth covering it. One of the Dionysian sarcophagi that might have been seen in the Renaissance does show the touch of one satyr's phallus onto the buttocks of another satyr, part of a suggestion of ritual intercourse. (You can see it on Daimonax's site.) It is unclear that the image was meant to signify something that actually happened in a ritual, but the Renaissance might have imagined that it did, in the "Bacchanalia." There was the Roman historian Livy's account that it happened in his day, in ritual intercourse by both sexes. He says it was a debasement of the original ritual. And of course these examples are a different order of magnitude than mere touch.
As far as the mere touching of a phallus, what the classical texts refer to is the touching of artificial phalli, at least to the extent of brides in Rome sitting on the phallus of the god "Mutino" (Cartari,
http://www.bibliotecaitaliana.it/exist/ ... 20Vincenzo) or "Mutinus Tutinus" (Hooper,
Introduction to The Priapus Poems: Erotic Epigrams from Ancient Rome, p. 3). And it seems to me that artificial phalli would have to have been touched by those who wore them as fertility charms, or perhaps bought them as votive offerings, in Renaissance Bruges (
Dixon, Bosch, also depicted in Cartari 1647.